Yes, Darcs predates Git by a few years and was used by GHC, XMonad, Happstack, and several other well-known Haskell projects.

git was first released in April 2005. We (Haskell community) were using dvcs through darcs for about 2 years prior to that. dvcs made a lot of sense to the Haskell open source world back then, as we didn't have servers, so central repos (like CVS or SVN) were out of the question. It had to be p2p to get off the ground.

IIRC, yes. Back then git was one of many of a new crop of DVCSs, and didn't have nearly the developer mindshare it has now.