I suspect the problem here is not "dwindling support for the current OSS driver" as much as the fact that you need to look in new places to see the activity.
Originally Posted by Panix
For 3xx-5xx 3D, the focus of activity is moving from the "classic" driver :
to the "Gallium3D" driver :
... and for display/modesetting the activity is gradually moving from UMS :
to KMS :
... although a lot of changes are still being made in both places.