uc_node_checkout 6.x-2.0-beta1

This new version is fully compatible with the latest changes in Ubercart as of beta 3. It also introduces new features sponsored by Commerce Guys related to attributes on the node add form and the association of multiple products with a single node type through some simple Views integration. I screwed up commits early on, so I'm dropping support entirely for the 6.x-1.x branch and asking everyone to update to this new version. Sorry for the trouble.