I for one like creepy filesystems that can't be read in another arch type processor!
http://www.microsoft.com/whdc/device/storage/gpt-64bit.mspx
http://www.sophos.com/support/knowledgebase/article/14726.html
http://en.wikipedia.org/wiki/EFI_System_Partition
Wonder if virus writers can make use of another partition to hide...
http://support.microsoft.com/kb/294773