It's possible that Monkey Island 5 will happen at some point (though probably just for PC). Whether we want it to happen, after the mess that was number four though, is another matter altogether...I'll never understand why they scrapped their PERFECT style and engine for the series from Curse Of Monkey Island for the shoddy one used in Escape From Monkey Island.
This could be the Star Wars game that's been rumoured to be being developed by LucasArts for Wii, but I could see them doing that in-house or farming it out to Ubisoft instead. Maybe it really is an all-new title, LucasArts have allegedly changed of late and want to go back to their 'golden age' with lots of new series rather than just relying on their old ones...
Whether or not this game comes to Wii, Free Radical will end up developing for the system. The company traditionally like Nintendo, since quite a few of them used to be in Rare and thus were close to them.