Technically, it's already a part of Wheezy. Just not the default. The packages are in testing already if someone were to wish to try it. Not sure how smooth the transition would go though.
From what little I've read of systemd (never used it myself), it's pretty fantastic performance. I'd look forward to it coming to Debian as the default for that reason.
But generally not enough of a reason for me to go out and try it myself, I hate fixing things if it were to break my system.