User blog comment:Dopp/Technical Update: Feb 28, 2012/@comment-1140008-20120229191140

"The Welcome Bot is being updated for Message Wall to be more compatible with how it has worked in the past: contributions will appear under User:Wikia and will be hidden in Recent Changes and Wiki Activity. They will still be signed by an active admin."

On the POTCO Wiki, the Welcome messages are still showing up on Wiki Activity Page.