Introducing or fixing bugs? A suggestion
 

Both as a mod author and user, I'm very disappointed with the quality of new releases. I'm not seeing a lot of the new "QA" method with a big set of quality tests before doing a release.
And when I upgrade my site to vB4 (which I'm holding off at this moment), I won't be upgrading any more to a maintenance release the day that it's released. I did that in the past, with a lot of trust. But now, it's gone.

For example, 4.0.1 introduced two big bugs hitting my DownloadsII mod: custom profile tabs are gone (including the blog one) and AJAX username/tag suggestion is totally broken because of some CSS change.

I've got one big suggestion for this: upgrade the vB.com forums when you "freeze" a release and give it to the QA team. We could have found those issues and you could have fixed them. Don't upgrade your forums two days after a release when it's already freezed a week before.