i have it unlocked with firmware 3.0 and all was working fine till last night, when the phone started telling me it was almost full whenever i tried to upload a file (80mb) via SCP. and it would fail at about 80% SCP throwing an error(im guessing the error meant that the phone was full) so i bring up itunes to see how much space is left on the phone, and it says over 3gigs... any ideas how to fix this?

There are partition for user and system ; In system partition system related files (such as os cydia ) are stored and its small partition. I hope you are copying files to system partition. By the way what is 80mb file you are trying to push?

i was uploading the file to /adam/

the file is a pdf file.

You are using system partition.

/ - system partion - small one for OS
/var - media partition (mp3,photos etc.) - big one for everything else

the best directory to store such stuff would be:
/var/root
or
/var/mobile
which are home directories for user root and mobile