Facebook can still give you notifications from the emails being pushed to your device, without it running. i.e. logged in, but menu-close out of the application.
It will not refresh status updates etc, unless its running.
"That's it then. Cancel the kitchen scraps for lepers and orphans, no more merciful beheadings... and call off Christmas."
I use facebook app everyday, checking or updating status every hour or so. I use Google serach (google app) about once or twice a day. I am logged onto to msn via beejive 24 hours a day, and read my news on viigo twice a day. With this kind of usage, I am not able to hit the 1GB mark. Hope this is a helpful comparison for data usage.
__________________ BlackBerry Tour 9630 | OS 184.108.40.206