bugtracker is also PG-only ...
For the future, could folks writing a package for just one database make a bigger effort to find folks willing to port to the other before we integrate them into a release?
Doing a port's not that big a job typically though it's fairly thankless. For many packages, though, I think we'll find that a call for volunteers will likely drag up at least one hacker who will want the package in their favorite DB rather than the implementor's favorite DB.
