Facebook is opening its activity stream to third-party developers via the Open Stream API. Now, in addition to status updates, developers will have access to other newsfeed content such as notes, photos and videos. Seesmic Desktop has already revealed plans for implementing the increasingly popular Open Stream API, which is set to provide a more holistic desktop facebooking experience.

In the world of browsers, Mozilla released Firefox 3.5 beta, equipped with a faster TraceMonkey engine, built-in JSON, audio and video tag support, and a private browsing mode.

There was also more news on the upcoming features in Windows 7 this week. Microsoft revealed it will be releasing a Windows XP mode alongside the Windows 7 release candidate version, in an attempt to help XP users switch to Windows 7 with ease. Another change to be included in the release candidate will be a more stringent security measure for USB drives. For a first look at Windows 7 RC, check out this photo gallery. The update has already been made available to developers, but the general public will have to wait until 5 May.

In other news from Microsoft, both Office 2007 and Windows Vista/Server 2008 are getting a second service pack update. Office 2007 (SP2) will be offering support for ODF and PDF formats, whereas Server 2008 (SP2) will get Hyper-V, amongst other features.

This week’s videos feature discussions about social networks, the Sun/Oracle deal and security-as-a-service.

–Posted by Lana Kovacevic.