Welcome to Smogon! Take a moment to read the Introduction to Smogon for a run-down on everything Smogon, and make sure you take some time to read the global rules.
Well there's a new game in the works. For now, there's just a trailer:
http://www.youtube.com/watch?v=orhOvbfyyJw
Also, for the 25th anniversary of the series, Mechwarrior 4 and its expansions will eventually able to be downloaded from Mektek.net.