Sprint hasn't released it yet, but an official Sprint update of the HTC Touch firmware has been leaked to the Web. The update brings the glory that is Windows Mobile 6.1 to all you Touch users. You can go get it over at the XDA Developers Forum.
I no longer have a Sprint Touch and so can't personally vouch for this file, but from the comments on the XDA Developers forum and over at Engadget Mobile, it looks like this is the real deal and "is a breeze to install." Proceed at your own risk, kids.