Apple added support for exFAT to Snow Leopard version 10.6.5.
ExFAT is available on Windows Vista with Service Pack and Windows 7 by default.
On Windows XP users can also install ExFAT with an optional download from Windows Update available where:
http://www.microsoft.com/download/en/details.aspx?id=19364
On Linux the support is limited.
It's manual mount. But you have to install exFAT Fuse from software update
and python-fuse, libmono-fuse-cil and gvfs-fuse.
Now in terminal
make a directory on media to mount the drive:
#su
password
# mkdir /media/pen
To see the partion name
# cat /proc/partitions
for example my is sdb1
then:
# mount.exfat-fuse /dev/sdb1 /media/pen
now it will appear on desktop
to eject
# umount /mnt/pen
More information about exFAT:
http://en.wikipedia.org/wiki/ExFAT