I found an "Automatically collect MMS messages" setting in the Preferences->Network tab of the Messaging application in my VWZ 700p earlier today. Its default setting was on.

I disabled this setting and left my data connection on since around noon today. In that time, my Seidio 2400 mAh battery drained less than 10%. Granted, I didn't make many calls or do much surfing, but without this setting disabled, my 700p was draining about 5% an hour with the data connection on.

Try disabling this setting and let us know if you get better battery life. When an MMS message is sent to you, you will be notified and prompted to retrieve it. (At least this is what happened on my VWZ 600 and 650.)

I also think that the 700p drains the battery by repeatedly looking for an EV-DO signal whenever it gets stuck with an 1xRTT signal, which happens to me frequently in the suburbs of Boston.