Apple's Roger Rosner announced iWork for iCloud today at WWDC. With this new iCloud tool, users will be able to fully edit Numbers, Pages and Keynote documents via their web browser regardless of the operating system they're working on. Yes, since iWork for iCloud is accessed via a browser you can even edit documents on a Windows 8 machine.
The most impressive feature showcased during the WWDC keynote was how powerful the programs editing capabilities were, despite them being available in a web browser. Users can drag and drop images from their desktop into their documents and have them seamlessly integrate into the document. Text editing includes powerful tools like context-sensitive formatting. In addition, iCloud can now add, convert and edit Word and Office documents directly from the web interface. For commuters who have to jump from computer to computer while traveling, this is going to be a big deal.
You can read more about iWork for iCloud on Apple's website.