What I don't quite understand is why this wasn't done prior to launch. But then, IANAL.
Microsoft is already facing lawsuits related to the just-launched Windows, with an operating system technology designer accusing Microsoft of ripping of its patent for "tiles."
SurfCast, in a complaint filed yesterday in a U.S. District Court in Maine, said Microsoft infringes one of its four patents -- No. 6,724,403 -- by "making, using, selling, and offering to sell devices and software products" covered by SurfCast's patent. That includes mobile devices using the Windows Phone 7 and Windows Phone 8 operating systems as well as PCs using Windows 8/RT. Microsoft Sued Over Patent For 'Tiles' In Windows 8 [news.cnet.com]
May be I'm looking at it too simplistically but to me the 'tiles' are just another way of displaying desktop icons, whether it's a folder or an app/executable. I guess Surfcast's main issue may be with the snippets of info that are displayed and dynamically updated within the tiles.
Still seems pretty flaky to me - the lawsuit not the design ;-)