http://www.truecrypt.org/docs/?s=version-history

6.0a

July 8, 2008

      Resolved incompatibilities / bug fixes:

    *

      On systems where certain inappropriately designed chipset
drivers were installed, it was impossible to encrypt the system
partition/drive. This will no longer occur.
      (Windows Vista/XP/2008/2003)
    *

      Other minor bug fixes.  (Windows, Mac OS X, and Linux)

6.0

July 4, 2008

      New features:

    *

      Parallelized encryption/decryption on multi-core processors (or
multi-processor systems). Increase in encryption/decryption speed is
directly proportional to the number of cores and/or processors.

      For example, if your computer has a quad-core processor,
encryption and decryption will be four times faster than on a single-
core processor with equivalent specifications (likewise, it will be
twice faster on dual-core processors, etc.)

      [View benchmark results]

http://www.truecrypt.org/screenshots2.php

      Ability to create and run an encrypted hidden operating system
whose existence is impossible to prove (provided that certain
guidelines are followed).  For more information, see the section
Hidden Operating System.   (Windows Vista/XP/2008/2003)

      For security reasons, when a hidden operating system is running,
TrueCrypt ensures that all local unencrypted filesystems and non-
hidden TrueCrypt volumes are read-only. (Data is allowed to be written
to filesystems within hidden TrueCrypt volumes.)

      Note: We recommend that hidden volumes are mounted only when a
hidden operating system is running. For more information, see the
subsection Security Precautions Pertaining to Hidden Volumes.
    *

      On Windows Vista and Windows 2008, it is now possible to encrypt
an entire system drive even if it contains extended/logical
partitions. (Note that on Windows XP you can encrypt an entire system
drive as well, but it must contain only primary partitions.)
    *

      New volume format that increases reliability, performance and
expandability:
          o Each volume created by this or later versions of TrueCrypt
will contain an embedded backup header (located at the end of the
volume). Note that it is impossible to mount a volume when its header
is damaged (the header contains an encrypted master key). Therefore,
embedded backup headers significantly reduce this risk. Also note that
a backup header is not a copy of the original volume header because it
is encrypted with a different header key derived using a different
salt. For more information, see the subsection Tools > Restore Volume
Header.

            Note: If the user fails to supply the correct password
(and/or keyfiles) twice in a row when trying to mount a volume,
TrueCrypt will automatically try to mount the volume using the
embedded backup header (in addition to trying to mount it using the
primary header) each subsequent time that the user attempts to mount
the volume (until he or she clicks Cancel). If TrueCrypt fails to
decrypt the primary header and then decrypts the embedded backup
header successfully (with the same password and/or keyfiles), the
volume is mounted and the user is warned that the volume header is
damaged (and informed as to how to repair it).

          o The size of the volume header area has been increased to
128 KB. This will allow implementation of new features and
improvements in future versions and ensures that performance will not
be impaired when a TrueCrypt volume is stored on a file system or
device that uses a sector size greater than 512 bytes (the start of
the data area will always be aligned with the start of a host-
filesystem/physical sector).

      For more information about the new volume format, see the
section TrueCrypt Volume Format Specification.

      Note: Volumes created by previous versions of TrueCrypt can be
mounted using this version of TrueCrypt.
    * Parallelized header key derivation on multi-core processors (one
algorithm per core/thread). As a result, mounting is several times
faster on multi-core processors.  (Windows)

    *

      Ability to create hidden volumes under Mac OS X and Linux.
    *

      On Linux, TrueCrypt now uses native kernel cryptographic
services (by default) for volumes encrypted in XTS mode. This
increases read/write speed in most cases. However, the FUSE driver
must still be used when the volume is encrypted in a deprecated mode
of operation (LRW or CBC), or when mounting an outer volume with
hidden-volume protection, or when using an old version of the Linux
kernel that does not support XTS mode.  (Linux)

      Improvements:

    *

      Up to 20% faster resuming from hibernation when the system
partition/drive is encrypted. (Windows Vista/XP/2008/2003)
    *

      Many other improvements.  (Windows, Mac OS X, and Linux)

This looked like a beefy release, so it seemed worthwhile.  I hadn't
noticed any other posts, so if I missed them I apologize for the
redundancy.