I’ve just installed bbpress and have the same problem – my posts were all -1years “freshness”
I figured out that I needed to configure the config.php with my server time and not my local time. My server runs on PDT, which is 7 hours behind my physical location (on BST, shortly to be GMT). So now my “freshness” is correct, but all my post times are wrong. I’d like to see a mod that allows the user to define their local time zone and operate independently of the board’s installation location.
Apart from that – bbpress looks great and I love the freshness of it after the clutter of phpBB.