Hey all, ckknight here.
As many of you have discovered, the Cataclysm Beta has opened up third-party (that's us) addon usage.
CurseForge and WowAce has added support for the 4.0 game version, and it's also recommended that in your TOC file, if your addon is compatible with 3.3, to make it look as such:
## Interface: 30300 ## X-Compatible-With: 40000
If it is 4.0-only, it would properly look as such:
## Interface: 40000
The packager will pick up on this and properly assign both game versions to the generated file. If uploading (CurseForge only), then you can select more than one game version. I still recommend using the X-Compatible-With paradigm, though.