Called sprint to pay my bill by dialing *2 and received an automated message that my PC6700 would be updated. Saw an "updating software" message on my phone. Then it showed it would autorestart after a 20 minute delay. I did a search and looked back 2 months and did not find anything. Anyone have an idea what was put on my phone?

I did not have to install a cab file when my phone came back on and nothing appears in the systems, connections, or programs folder.

this is whats known as a PRL update. this updates the roaming list on your device so it knows what towers to roam on. search for "PRL" or "preferred roaming list" to read up on it OR do a search on the internet for "PRL". this has been discussed many many times...
if you need more info, contact me and ill see if i can help...