Drupal 5 contrib modules started workin en-masse about 3-4 months after its release. There are still some biggies that need to be done for D56: Views2, CCK, etc.

Right now I'm just hoping ubercart 1.0 can be released so I don't need to backport anything, or branch my own ubercart v6 code. We have a fairly strict time line to get ubercart in D6 by the end of April... time is ticking!