Ok, I checked it out and the problem that I think Google would have with this is that they have no way to make money from it. GMail is supported by the advertising that you see when you sign-in and view your email through a web browser. The Gmail drive utility is definitely very cool, but because it’s so well integrated into Windows Explorer, there are no ads.
It’s a very cool application though, and Tigerblade is right — there is a lot of goodwill at Google. Probably as long as it doesn’t become too popular and get abused (which quite honestly, I don’t think it will… because of the $1/GB thing I already mentioned), they’ll quietly ignore this program and let it exist. If it attracts too much attention though, look for that to change.