As far as I know, there are no kits for ANY of the official Arduino boards (and the Uno is almost all SMT, so it wouldn't be much of a "kit")
Yes, a Freeduino design could be updated to have the new USB controller (assuming that that is the feature you're interested in.) That would require that a Freeduino vendor be willing to go to the effort. At the moment, it doesn't seem like there are many compelling reasons to do so.
There would also be the USB VendorID issues that have been discussed exhaustively in other threads...
It would be interesting if someone were to do a USB/Serial board using the the Atmel USB chip; that would give Uno-like USB capabilities to any of the arduino boards...