iWork for iCloud is a brand new product announced by Apple today at the WWDC keynote. It's a product that will coexist with the currently existing iWork suite. iWork for iCloud exists totally in the cloud, meaning that it runs via Safari and other browsers (IE and Chrome included), similarly to Microsoft's Office 365.
Editing and viewing documents in iWork for iCloud looks almost identical to the current iWork suite experience. Support for Pages, Numbers and Keynote (along with 3D animations) is included.