8.2rc1: vacuum full fills up disk space

this somehow sounds buggy:

there's this table forum.posts which had 224mb table size, 145mb toast table size and 176mb indexes size (aproximately 60'000 rows). as i was doing some updates of all the records, i've issued a VACUUM FULL <tablename>...

this was merely 60min ago, and it hasn't yet finished... instead in pg_xlog there are now 380+ files, totalling in over 6gb. available disk space is almost used up...

the table was freshly loaded yestertday when reloading for rc1.

as the process of vacuuming is still ongoing, is there something i can do to...
a) .. prevent total diskspace fillup. what happens if i send a cancel signal to the process?
b) .. gather some "evidence" if needed?
c) .. check if the vacuum process is still alive?
d) .. give the process in question a higher priority so it would finish sooner?

thanks,
thomas