That is a neat idea. I was sort of thinking of that, but was concerned about invalid and unused database objects.

You'd avoid name collisions pretty handily, though. I'm guessing that you would just need some policy to drop all of the old versions after some period.

You'd also just need to bundle grant exec statements with the procedure DDL.

That would work well with Oracle and DB2 as well. I'm not totally sure about SQL Server, though.