It's finally coming as the video below shows. In game XMB will soon be hitting PlayStation 3s everywhere and it looks just like how you would think it would like. One great thing I really like is you can switch games pretty easily since the entire interface is overlayed onto the current game you are playing. With Xbox Live, you would have to quit out to the main menu and then scroll to the game you want to play and start it there. Now the interface for Live is more visually complicated so it's a different experience but for simple and quick change of another game on your system, the in game XMB works well. Using your own music for games is also shown and it's nice to be able to change to something you want to listen to while playing a game. Trophies is also mentioned but not shown as that's in the next video. At the end, the demonstrator does say MOST games are supported so we'll have to see what games currently won't work with in game XMB and if they will be updated to do so but so far I like it. No invites to games while playing is shown and if I remember correctly that wasn't listed as one of the features so I'm hoping it does make it in there somehow.
Thanks
Kotaku.