When Microsoft first created its Office Web Apps, they were designed primarily as tools for reading and performing light editing of Office documents. That goal is now evolving, and the apps are growing into more fully featured Office experiences on the Web.

Today, the apps are receiving their first big update to achieve that goal with the addition of a feature that's long been a core of Google's App experience: real-time co-authoring. The Word, Excel, and PowerPoint Web Apps now all support simultaneous collaborative online editing. In Word and Excel, the co-editing is fine-grained, with per-character and per-cell granularity. PowerPoint is a little coarser, with per-slide granularity.

The apps also include a range of new editing facilities. Word has search-and-replace, support for headers and footers, and rich formatting of tables. The Excel Web App is adding the status bar quick analysis (sum, count, mean) feature found in the desktop app and is now compatible with protected sheets. Also, PowerPoint can now crop images online.

The next big thing that Microsoft intends to add to the apps is to enable editing on Android tablets.

The Office Web App update starts rolling out today and should be available to all Office Web App users, both through SkyDrive and Office 365, by the end of the week.