The major differences are that there's a bit more green and that the app drawer fades in/out. In my minute or two with it, that's about all I noticed, and really, that's all you can ask for at this point. That said, if you're using vanilla Froyo now, there's really no downside to using the Gingerbread launcher.
Nothing revolutionary, but given the amount of fervor over Gingerbread, the launcher and the keyboard may be just enough to whet your appetite and hold you over until some official releases start rolling out.
You can find the app in the Market (search "Gingerbread Launcher"), at AppBrain, or just by scanning the QR code below.