TrueCrypt Cross-Platform??
Since I have an iMac with OSX 10.5 (Leopard), I use TimeMachine for my backups. This works great actually. But I also need an off-site backup of some sort. Just in case the house burns down or that some f*cker decides to steal my hardware.
So I bought an external Freecom 160GB USB2 drive (USB powered) for my off-site backups.
I encrypted the entire harddisk with TrueCrypt 5.0 on my iMac, and copied the data I needed to preserve. After that I wanted to access the data from my work laptop (Windows XP SP2 with TrueCrypt v5.0)….. This didn’t work. TrueCrypt didn’t recognize the password, or the encrypted disk (AES / SHA-256 full disk encryption).
I tried to access the data on my Mac and everything worked, so there’s no data corruption of some sort. Eventually, I recreated the encrypted drive on my Windows XP laptop (lost the backup in the process). This time the disk would mount, and could also be read/mounted by my Mac.
So, I guess that TrueCrypt is Cross-platform, but with the current version (v5.0a) you need to make sure to create the volume on Windows if you also want to mount it on OSX.
I reported this through their bug-reporting tool to the developers. No idea if there are similar problems with Linux.
UPDATE: Pretty soon they released v5.0a, and today v5.1 was released. So development goes on 
