i prefer SMF over phpBB... phpBB has a past of security issues, but lately they have been good in keeping security in good standing order. SMF has a lot of good features and support, where phpBB is more popular then SMF, it just does not have the functionality of SMF when it comes to mod installs, or a loyal community that is constantly thinking up ways to improve it. it really comes down to, what you like and what you want to do with your forum and how much functionality or lack of, you want.
According to their site the beta is available to charter members since August. I don't know when 2.0 will be done testing but when it is it will be good.
I'd go SMF. phpBB 3 maybe too if you check that out! I loaded it a bit, just looked around - the design was OK, the admin panel was kinda nice, but didn't really test-run it