I tend to work a lot with both Git and Mercurial, and to ease the pain of forgetting which I'm using at a given moment, I created a setup I described on another post. An even better solution is having all this sorted out on the server side, so that it doesn't matter which of the two I'm using. This comes in a form of a product named Kiln Harmony, which also turns out to be a complex beast behind-the-scenes. Would be kool to see a FLOSS implementation of this.