First off, I apologize for my late response to this thread. I did not have an account with SQL Server central and have just now created one.

Interesting question. I did think about this when I originally read about SSB and people do ask me this question when I deliver sessions on SSB. SSB sure comes close to MSMQ in several ways, but the first thing that I would consider before using SSB is: Do I want to do asynchronous operations in the database? If so, then SSB is for you. Second, SSB requires that both ends of your communication are SQL Server 2005. If this is the case, then again SSB is for you. Third, if you do require transactional message processing (and the above two points hold good), then SSB is for you, since transactional semantics are built in.