Based on some quick tests, I've noticed the following: if you kill the Google Messaging Service, Chrome to Phone (a.k.a. Send to Phone) will stop working. This seems rather obvious, but I had been in the habit of killing the Google Talk Service (GTalk) prior to Froyo. After Froyo, it looks like the service was renamed/replaced with Google Messaging Service. I suspect that killing the Google Messaging Service could affect other Google services too.