Does using TrueCrypt makes "file shredding" tools obsolete?
Solution 1:
The deleted files still lurking in the filsystem (that Eraser would delete) will be encrypted as well, as the whole filesystem is encrypted. So it ends up with how secure one thinks it is to encrypt the disk with TrueCrypt. One can only find the deleted files if one can get access to the crypted filesystem (with password or cracking it).
Solution 2:
The only way to completely protect data is to destroy all copies of it beyond possibility of recovery. So yes...shred your disks. And if you've memorized any of the data, shred your brain too.
http://xkcd.com/538/