AFAIK all standard 11.4 repositories + Tumbleweed.
Additional repos: use preferably tumbleweed versions, but 11.4 should also work.
for example: you need only Packman Tumbleweed (Packman 11.4 is not needed), but if there is no tumbleweed version of particular repo (for example Wine or Virtualbox) - use 11.4 version.
All repos should have equal priority.
When openSUSE 12.1 comes out, you will have to change all 11.4 repos to 12.1 repos. Tumbleweed repos will stay unchanged (probably ).
You don’t need ALL the repos enabled.
For example src repos are needed only if you want to compile your own openSUSE.
So for core Tumbleweed system you’ll need only OSS, NON-OSS, Contrib and Update repos from standard 11.4 set (plus Tumbleweed of course).