Office Live for Small Business is a web site that is hosted by Microsoft, often without charge, which your customers can visit as your public web site. It also has a number of applications behind the scenes that you can also use, including Workspaces that you can use to share documents securely with select clients without emailing them back and forth.
Personally, I would recommend you do not try to host your customer web site on your SBS 2008 system. Office Live for Small Business is a convenient way to have your SBS 2008 system collect email and provide remote access to the business while having a public web site on the same domain name that is hosted by someone with greater reliability of communications and more bandwidth.
You can see the current benefits from the web site http://smallbusiness.officelive.com. At the moment they are in summary:
Free web site—Create a free web site for your business so that customers and prospects can...