It appears that Infinity Ward is aware of the outcry from the PC gaming community over the recent announcement or about Modern Warfare 2's multiplayer. FourTwoZero has a post with information on the new IWNET, how it works and why it will be better. You can read it here.
Now that you've read it, I would like to say that it sounds an awful lot like how multiplayer matchmaking is handled on a console. Rainbow Six Vegas 2, FEAR 2, OFP: Dragon Rising; these are a few of the shooters that I have that I can name off the top of my head that have similar matchmaking multiplayer and they all blow to play on the PC. The model seems to work great on the console, which I like when playing on the Xbox, but not on the PC.
I do like that the friends list that was introduced in World At War is coming to MW2, but that's about it. Which is unfortunate because I was really looking forward to getting this, but the increased price plus the crappy matchmaking has convinced me to scratch this off my list for now.