there is a changelog in the main directory of the game (TPC changelog.txt). starts from version 0.5ish till present (released). Version 0.7.1 will probably pop out next month, along with its own changelog as always.
I know 0.7 brought a lot of big bugs and practically makes it impossible to enjoy, but I can say that next patch drastically improves game functionality (and makes multiplayer more fun).
As far as I know, multiplaying TPC is done mostly via Hamachi networks between already acquainted players, with a preset meeting point and date. Not sure if the community is big enough to hold an official TPC server, but it is definitely an idea worth considering in the future.
I myself for instance hang out with some guys from time to time at this network:
057-794-093 - hamachi WBC network. No limits, no password.