The benefit of not waiting, since other big names (Microsoft, Apple) have announced they will be focussing on this, is that when the technology becomes mainstream, Ubuntu will be ready, and the software not be in early alpha stages or so. I think it is a safe bet that this technology is going to actually be mainstream in the foreseeable future. :)
"Multi-touch is for heterosexual foreplay, not computer interfaces."
Okay, so you don't care about it (me neither by the way). Thing is, it just might be pushed into the mainstream by big vendors, and then Ubuntu just sits there, unable to do anything with it, and people will think "gosh, lousy operating system, windows and os x can do this".
The real question would be:
Will the various window-managers & apps be ready ready to take advantage of this functionality?
Would be REALLY very cool to manipulate stuff like Compiz 3D-desktop with multitouch