Actually, this was happening and resolved last weekend (Feb 4th-Feb 7th), but I'm just now getting around to blogging about it (bad Doug!).

Apparently resize2fs is broken in fc3. There's even a Red Hat bug about the problem. Of course, I discovered this the hard way ;)

Turns out resize2fs (used in offline partition resizing) is broken in Red Hat's e2fsprogs 1.35 that comes with FC3; the developers for e2fsprogs fixed this and can even repair damage caused by the broken util in e2fsprogs 1.36, which Red Hat hasn't released yet. So for now you need to use ext2online to resize partitions in FC3.

And btw:

$ df -HFilesystem             Size   Used  Avail Use% Mounted on/dev/mapper/StorageArray-lvol0                       923G   479G   444G  52% /mnt/bigdisk