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 tabl=
e size and 176mb indexes size (aproximately 60'000 rows). as i was doing so=
me 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 a=
lmost 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 t=
o...
a) .. prevent total diskspace fillup. what happens if i send a cancel signa=
l 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 soo=
ner?

thanks,
thomas