Ever since Pieter Knook mentioned it in his keynote, the WM Community has been all atwitter about ZenZui. Near as I can tell, it's a combination of two major things: a fancy thumbable interface (that's also friendly to T9 phones) combined with a unique way to provide and cache mobile content.
With ZenZui, your phone screen is a portal into your own customized Zoomspace, an information landscape of personalized, cached content in the form of Tiles that directly reflect your lifestyle. Using a single thumb, you fly in and out of your Zoomspace – two simple taps get you directly to any Tile.
The "Tiles" allow you to zoom in and out of the content you're looking for relatively quickly and easily - it's actually a really smart way to build an interface. Take a look at the embedded YouTube Video after the break. The content comes from two directions, apparently: tiles created by companies and tiles created by independent developers - the users pick their favorites and share them with each other "virally." Basically it looks like ZenZui is trying to get money to folks without making us users crazy with ads and spammy content and whatnot.
In any case, it makes a little more sense when you watch the video. It'll probably make even more sense when we use it. I'd say this is a good idea without a future, but it's a Microsoft spin-off, so I'll say it's a good idea with a good chance.