The Amazon App Store is now open for business. The store officially opened last night, and currently has 3,800 Android applications available.

Amazon has been trying to recruit developer to its store since January of this year. The store scored exclusive rights to sell the Android version of Angry Birds Rio, a huge win for a store that wasn’t even open yet. Apple is also already suing the store for using the name “App Store,” a name that it has trademarked.

The store puts itself in direct competition with Google’s Android Marketplace, which currently has close to 200,000 applications. In order to stay competitive, Amazon is offering a “test drive” feature that lets customers try out applications before they buy, one-click purchasing for customers that have a credit card on file, and a free application a day to get potential buyers into the store in the first place.

Have any of you checked out the Amazon App Store yet? What do you think?