THEBLUENOWHERE  This is an excellent cross-platform solution to keeping things secure! I have no problems with this and it gives me different ways to encrypt volumes for various tasks eg. From storing my bank details to my plan to take over the world.  
(Version 6.3)

THEKIDFROMTHEREDBANK  I'm having several issues under Snow Leopard. Trouble with mounting the device, trouble when backing up on the device. Get system crashes -> have to force shut down...

Please fix this. This would be essential.  
(Version 6.2a)

LUMINOUS  One of the BEST decryption/encryption tool for Mac and Windows!

6.1 is much more faster!!

By the way, which is the most secure encryption?  
(Version 6.1)

FOLLEREC  Just installed TrueCrypt and I find that, despite some quirks, it's great for my purpose: accidentally losing my flashdrive that contains confidential company information.

I sometimes have to bring home confidential stuff like financial documents, sometimes passwords in plaintext (i really should start using KeePassX for that), etc. Now I encrypt my entire flashdrive. This way, if I drop it or lose it or get mugged, any confidential information I have on me is protected. Whoever gets my flashdrive can have it.

It's great too that it's cross platform, although the compile on CentOS 5.2 was a bit of a hassle (not enough clear documentation on this yet). But at least I can use my encrypted flashdrive on Linux, Windows, and, last but not least, my Mac. DMGs are great but obviously out of the question when you're working on multiple platforms like me. TrueCrypt is the solution for me.  
(Version 6.0a)

GERBER  (All the comments in my previous review of version 5.1 still apply unless noted here.)

TrueCrypt 6 is a nice improvement over 5.

Hidden volumes are now supported, and therefore plausible deniability. There are also major speed improvements, which I did not confirm, but I was able to play back video from the secure mount without trouble.

It turns out that HFS+ volumes are possible (and were in 5.1 as well), but you have to re-format an existing FAT32 secure disk. These disks won't be cross-platform, of course, but they'll perform much better.

The Mac (and Linux) version still lacks a traveler/portable mode as well as boot disk encryption.

With the addition of hidden volumes and its excellent security algorithms, TrueCrypt is indisputably the top encryption tool on the Mac.  
(Version 6.0)

GERBER  This is one of the top encryption tools on Windows, and it's great to see it on the Mac. It offers highly secure encryption for file volumes (disk images) and filesystems (not including the boot drive/partition). In my testing it was stable and performed fairly well. (Equivalent to most other FUSE-based filesystems)

Unfortunately, the Mac version falls flat in many ways compared to the Windows (and Linux, in some cases) versions of TrueCrypt. These limitations limit the usefulness of TC, especially compared to other options on the Mac. Specifically:

Hidden volumes are not supported, and therefore there is no standard of plausible deniability. The fact that there is encrypted information and the quantity of it is obvious to an adversary.

There is no "traveler" mode, so you cannot keep encrypted volumes on a portable disk without installing MacFUSE and TrueCrypt on each system you need to access it from.

There is no encryption of the boot drive. However, external drives can be fully encrypted.

It only supports the FAT32 filesystem. Native HFS+ is not supported. So you have to deal with .ds_store files, etc.

It relies upon MacFUSE, which is something of a moving target as it's under active development. This also creates a potential security weak point that the TC authors would not necessarily be in a position to correct.

Given all of this, Disk Utility's encrypted disk images are, in many ways, superior to TrueCrypt. TC is more difficult to use (it's distinctly un-Mac-like) and less widely supported on the Mac.

While the encryption is stronger (512 bit encryption vs. 256 bit in Disk Utility), neither can be readily compromised through brute force. There is also some security in TC being an open-source project. Apple's implementation of secure disk images has not had nearly the review that TC's has.

The one real advantage of TC is that its encrypted disks are cross platform. Or, more accurately, the Mac version of TrueCrypt can access Windows' TrueCrypt volumes.  
(Version 5.0a)

DAVE BURBANK  TrueCrypt has been around for a while on the Windows platform. I first learned about it when the great "Security Now" podcast devoted an entire episode to it. TrueCrypt is now available for OS X and there's a new GUI version for Linux. This is great! I use Truecrypt to encrypt the data on my many USB Flash Drives. I can now use these encrypted flash drives on all three platforms. TrueCrypt can encrypt entire volumes, partitions, or you can create an encrypted file (kind of like a disk image) onto which you can store your most important data.

There is so much that TrueCrypt does. I have only scratched the surface. Listen to the Security Now podcast on TrueCrypt. The TrueCrypt is extremely thorough, but needs to be completely updated for Mac and Linux.  
(Version 5.0)

ENIGMAH  works great for me on leopard intel.  
(Version 5.0)

KP.GORES  Leopard, PPC. I have installed MacFUSE with additional filesystems and this works ok.

TrueCrypt creates a volume, but when trying to mount it I get an error message from hdiutil telling me there is no filesystem. Please, help  
(Version 5.0)

RLOOMANS  The description is wrong.... encryption of the boot drive is only available on Windows.  
(Version 5.0)