Installed the official 5.5 carrier file on my 3Gs with 3.0, rebooted.
Can send MMS
CANNOT RECEIVE MMS - when an MMS is sent to me, I get the tri-tone alert and then I lose all network/data connectivity. Signal strength bars, AT&T, and 3G icon disappear and I get "searching..." then it reconnects me to 3G.
I have rebooted, and reset all network settings and still cannot receive an MMS with out it killing my data connection.