TrueCrypt is free (as in beer) software used for on-the-fly encryption of data, but it is not licenced under open source licence.
tc-play is free (as in freedom) tool whic provides full support for creating and opening/mapping TrueCrypt-compatible volumes and it is licenced under GPL licence.
Because TrueCrypt software is under a poor license, which is not only non-free, but has the potential to be actively dangerous to end users or distributors who agree to it, opening them to possible legal action even if they abide by all of the licensing terms, depending on the intent of the upstream copyright holder. Fedora continues to make efforts to try to work with the TrueCrypt upstream to fix all of the issues in their license so that it can be considered Free, but have not yet been successful. - taken from Fedora Forbidden Items page.
There has been no articles regarding tc-play, and that seams strange since it provides great functionality, hopefully some reviews and tutorials will soon follow.