Got the text too. Talked with a guy at a T-Mobile store in my neck of the woods
and he recommended I do a factory data reset after the update and download all the apps I had off the new market.
Looking forward to it, just don't wanna have my slow (well, next to my Mom's new 4G) phone be even slower trying to push Froyo. I've read good and bad re: the 1st 3G update so I'll take the gamble.