Apple announced the release date for the Mac App Store. The store, which will open on Thursday, January 6, will feature apps in a wide variety of categories, including Education, Games, Graphics & Design, Lifestyle, Productivity and Utilities. As on the iOS App Store, both paid and free apps will be available.

MapQuest announced the launch of a U.S. site built on OpenStreetMap data. The project, which is open source, plans to encourage community participation in map building.

Research from the mobile ad network provider InMobi found that iOS is the most popular mobile ad market in European markets, with a 31.9 percent share. Nokia has a 19.7 percent share and the Android OS has a 12.9 percent share.

AOL bought Pictela, an New York-based branded media startup with a focus on bringing video, photos and apps-based ads into online advertising and social media. The terms of the deal were not disclosed.

Hosting company Rackspace bought Cloudkick, a Y Combinator-backed startup which focuses on providing a server management system to businesses. The terms of the deal were not disclosed.

Twitter raised $200 million at a valuation of $3.7 billion in a funding round led by Kleiner Perkins.

eBay bought Critical Path Software. Critical Path Software. is a Portland-based mobile app developer, that will most likely help eBay with its mobile apps. Terms of the deal were not disclosed.

Facebook is adding face recognition to its photo tagging feature. The software will attempt to match new photos to existing photos a user is tagged in. Users can disable suggested tags in thier Privacy Settings.

The Pew Research Center’s Internet and American Life project released the findings of a study on age and technology use. It found that younger users are more likely to regularly visit social media sites and adopt new technologies. (Wow!)

SpotXchange, a video advertising network, has raised $12 million from H.I.G. Growth Partners. The company had previously raised an undisclosed amount of angel funding in 2008.