Back on October 2006, Google acquired JotSpot, a hosted wiki platform for building collaborative Web sites. But it wasn't until now that Google revamped the service and launched it as Google Sites. The new application comes as an addition to the Google Apps suite that is set to challenge (on the web) the behemoth that Microsoft Office is, and try to lead the already somewhat crowded market for collaboration office applications based on the web.
Google Docs has also received a cosmetic upgrade, one that seems to resemble more the actual Office suite from Microsoft. It may sound ironic, but I believe it's a stable desktop-based component that these web services are lacking to become truly mainstream.