Google's been on an acquisition spree recently. In the last few months alone, it's acquired ReCaptcha (for scanning books), AdMob (for mobile advertising), On2 Technologies (for video compression) and Teracent (for targeted display ads).
Now you can add a fifth acquisition to that list. Google has just acquired AppJet, the creators of the real-time collaboration word processor EtherPad. In AppJet's announcement, the company revealed that its product and its staff will become part of the Google Wave team.
The actual EtherPad service will stay up for another four months, until the end of March 2010. After that, it will shut down, as the team will focus on Google Wave.