This happened to me. After downloading 3.0, I found my employer did not have me on the appropriate data plan, which they kindly fixed. But the "SMS" had disappeared from the icon on the phone. No error message, I send a text, and it goes out to the ether, and I receive nothing. I suspect it may be an ATT problem, but I was hoping that there were some common experiences. After all, I fixed my ringtones by renaming them!