Messages DOES work -- but to get the messages to come through on your computer there are a couple things that have to happen.
#1 - the Messages app must be active on your computer. (i.e. the app must be open)
#2 - the person sending the iMessage has to be sending a message to your email address - NOT your phone number.
Most people still send text messages via a phone number, even those with iMessage/iPhones. While those will go through fine iPhone to iPhone - they won't go through to iMessage. Hopefully the "unification" in iOS 6 will solve that problem.
I finally figured out what the problem was. My wife's iphone's messages settings were logged in with my ID. All is well now but that being said, it seems a bit lame to always have to have the messages app active on my computer. If Apple is trying to make the OSX experience more like IOS, it should push alerts and messages through regardless. An app doesn't have to be open on my iphone to get an alert.
Also, I find it interesting that even sitting in my house with my computer, iphone and ipad on my wifi, all 3 get a message at different times. Yesterday, I got a message, answered it on my iPad and about a minute later I got the same message on my iPhone.