Thanks! I was going to be approaching this next on my Donations dev to do list. You have saved me some time!
My goal is to have a configuration module that will allow you to determine a donation level that would be mapped to a group. As such, you could have a simple one group "sponsors" as you mentioned, or you could have 5 levels (for example) each with a different group of varying permissions, etc.
If implementing this proves too cumbersome for a quick job, I will be turning in just a basic version for now.
Again, thanks!
-Jeff