There are really three options for you once you decide to put your business on Facebook (well, four really, but three "good" options).
Choosing a Facebook fan page
A Facebook fan page is very easy to set up. It allows you to choose a category of business or interest and include your business name, website, etc. You would log in with your "Jon Smith" personal Facebook profile, then set up the "ABC Company" fan page. When you post on the ABC fan page, you are posting AS ABC. That also means if you personally "like" a link on your own page, ABC "likes" the link, not Jon Smith.
Having a Facebook fan page also makes it easier to place ads with Facebook. Facebook is constantly offering you to take advantage of their "Sponsored Stories," on the right hand side of your fan page. If that is something you wish to do, you would follow a few steps and then your ad will be ready for approval.
Facebook fan pages also allow your fans to write "Recommendations," which will also appear on the right hand side of your screen. This is a free service and most times when a fan comes to "like" your page, Facebook will ask immediately if they would like to write a recommendation. You may also ask your fans to come to the page and write one.
One current issue with fan pages is that people cannot generally tag photos with a fan page profile name. They usually can, however, tag a comment. So if you want to tag a fan page, I would suggest posting a photo and then making a comment below it, tagging the fan page. Facebook could very well be in the process of fixing this, as you used to not be able to tag fan pages at all in comments. When in your fan page, you can also use Facebook "as ABC Company." This is a fun feature if you'd like to post as ABC, however, as of the posting of this blog, you can only post on other fan pages -- not in groups or on personal profiles.
A draw-back (to some, but not to others) is that fan pages do not allow private messages. All postings to ABC Company will be made publicly on the Wall. This is fine if you don't want an overflowing in-box. This can be bad if customers have issues that they are now posting publicly on your company's fan page wall. Also, your personal Jon Smith Facebook profile does not automatically link to the fan page (unless you choose to publicize administrators), so people may not know that John Smith runs ABC Company's fan page (although, that is a positive for most). Therefore, if you had hoped customers might send you a personal private message, that might not happen.
Fan pages seem to be a good option for those who are planning to have many, many fans posting in their forum.
Creating a Facebook Group
Facebook groups are often great for a more interactive experience. When something is posted, or commented upon, it automatically moves to the top of the feed so that the popular posts are easy to find. You can control the settings to make it secret, closed or open, based on who you would like to have posting in the group. You also get an e-mail address associated with the it so that you can send e-mails to the entire group from your personal e-mail account. Do not, however, underestimate how grumpy people can get when they receive unsolicited e-mails.
Most people who dislike groups, however, complain that they don't like how they are added. If you add a friend to the group, they are automatically placed in the group. It doesn't ask permission of the friend. They can easily leave the group, but I have seen many an argument go down in different groups over people being added without permission. Also, if you, Jon Smith, posts in the group, you will be posting as Jon Smith, and not as ABC Company.
Group members can very easily set up photo albums to share with other members. You can also set up group chats and events or share documents.
Groups seem to be especially great for smaller(-ish) groups of people who like to set up get-togethers or share photos -- for example, like a dance studio or a fishing club.
Setting up a Facebook profile for your business
A third option for your business is setting up a personal Facebook profile for ABC Company. This means you would have two Facebook profiles -- one for Jon Smith and one for ABC Company. You would need two separate e-mail addresses and log-ins. For those who mostly want to use Facebook AS their company name, this is a fine option. For those who don't want to maintain two separate profiles, it can be time consuming.
People can send you private messages, or choose to post on your wall. You can also create a Sponsored Story ad using a profile. Your customers cannot write a Recommendation, though.
Your friends/customers may not create photo albums. They can, however, easily upload a photo to your wall or tag you in their photos.
The fourth, not-so-great option I mentioned is the Facebook Places page -- basically Facebook Places is the entire phonebook dumped into the Facebook database to list companies all over the world. It looks much like a fan page, which can cause confusion, but doesn't have all of the functionality of a fan page. It allows people to "check-in" to places even if those companies do not have a fan page. This created dual profiles for those companies who did take the time to create a fan page already. Facebook is apparently working behind the scenes to allow companies to merge their fan and places pages. However, if you wanted to try to run your places page like a fan page, you could certainly try it.
I would suggest that if you are going to put in the effort, create a fan page, but keep an eye on the places page to make sure you aren't missing any postings by customers who aren't aware of the difference.
So those are your options for getting your business on to Facebook. Each option does have certain positives and negatives, so you may want to make a list to decide which will work best for you. What I would not recommend, though, is trying to maintain all three (or four) options. It can get confusing and be extremely time consuming.
In the meantime, if you need help getting your business on Facebook, Social Sonar would be happy to help!