The interesting thing about openSUSE and it's Build Service is that the barrier of entry is zero. No contributor agreement, no sponsorship required -- in contrast to Debian (the strictest), Fedora and Ubuntu. Unless things have changed since 2007, that is.
If you vet your contributors, then you can afford to trust them a bit more in deciding what's stable and what's not. It's not without fault -- developers are humans, after all. But it's interesting to see what solution openSUSE ends up with.