First off, halleluja:
Signal Studios are dropping GFWL in favor of Steamworks, which means there's a chance they might be able to implement multiplayer, either for the original Toy Soldiers, or for Cold War once that's released.
There's been a lot of speculation that the reason why they left it out on the PC was because GFWL is such a shitty program, and based on the disastrous functionality of other titles like Gotham City Impostors, I think that makes perfect sense.
I just bought Cold War on the 360 the other day, and it's a seriously great game. Aside from catering to my Flashpoint-era military fetish, it just adds more than you'd ever expect to what was already a pretty solid game in the original Toy Soldiers.
Highly recommended. But I'd say multiplayer is roughly 50% of the game, so if you have the choice, you're better off with the 360 version.