For various reasons, including running a very old version of the phpBB system, I updated the forum software yesterday. Other than looking a little nicer, you should not notice any changes. (One note is that it will take a while for google to index everything, so if you try a search it might not work well.)
The most important change you may see is that if you had an old account, but never posted, it might have been deleted. One of the reasons this was necessary is spammers were exploiting a hole in the old forum code and generating 100 or so new accounts per day, and some of those were creating bogus posts. I deleted 200,000 accounts, and I dont think many of them were from actual users - if I accidentally deleted yours, I apologize, please feel free to re-register, your old account name is likely still available.