I have three drives plugged into my i7 MacBook Pro, and FCPX sees my LaCie FW800 500GB and WD USB2 2TB drives no problem, but refuses to access my LaCie FW800 1TB drive. Crucially the drive it is ignoring is formatted as NTFS whereas the other two are HFS+ (I'm using Tuxera NTFS to enable reading and writing to NTFS volumes).
This sounds like an obvious problem but I have rushes for several projects on the NTFS drive that I use in FCP7 (the rushes are stored there, but the actual project files are on my internal HFS+ volume - FCP7 does not save project files to NTFS, go figure).
Is this a possible explanation? Is FCPX ignoring drives based on the hard disk format?