I was pubbing TF2 on a joe.to server, and if you played awhile ago, you might remember the joe.to SF servers. Anyway, the map changed and suddenly I'm on sf_basin as a Demoman, blowing up the enemy front wall with sticky bombs! Combining SourceForts and TF2 gave me a huge game-boner.
I grabbed these screens from the joe.to forums:
It was actually really fun. It's funny to see a Scout using a crawl-tunnel to cap, like some weird game-universe-overlap. I'd like to see how other SF maps play within TF2, or how TF2 classes function in SF...