Unfortunately I wasn't so preventive: I installed D7 first and now I'm trying to bring Ubercart into life on it. The case is not so bad, however, the latest download is beta3 and it is only four days old. It means the activity is on the development and not on refreshing the site. What can be frightening: the dependency modules are also in beta and/or v. 1.0. Maybe there will be some result by the end of the week.