A few weeks ago we start experimenting with Git for Rails development.
I am not going to highlight the all of the advantages of using git here, but let me mention that Git is one of the few SCM out there that really understands merges.
As Linus, the creator of git, says "in this thread":http://www.gelato.unsw.edu.au/archives/git/0504/2182.html
bq. "The important part of a merge is not how it handles conflicts (which need to be verified by a human anyway if they are at all interesting), but that it should meld the history together right so that you have a new solid base for future merges.
In other words, the important part is the trivial part: the naming of the parents, and keeping track of their relationship. Not the clashes.
And it looks like 99% of SCM people seem to think that the solution to that is to be more clever about content merges. Which misses the point entirely."