I caught the announcement on a RSS feed last night, checked this morning - "not ready yet". They've updated the mobile site to now have a link to the 3.0 beta, but it currently says "...we're working hard to get it ready for you today - even if it's by the stroke of midnight".
Try checking again (http://mobile.yahoo.com/
from your BB) later on tonight, I for one am hoping for performance increases and more Flickr widget options. The big news is that 3rd party people can now build widgets to integrate into the code (using APIs and a SDK) which they hope to release within a month.