Google just announced that it has added a new layer of security to the Android market to keep malicious software out of the store. Android's generally open structure and the fact that the Android Market doesn't employ the same kind of restrictive policies that Apple put in place for its store mean that it's relatively easy for malicious Android software to be distributed through Google's app store. With this service, which Google calls Bouncer, the company actually runs and analyzes the software on its own infrastructure before the app appears in the store. Interestingly, Google notes that Bouncer has actually been active for quite a while now, but this is the first time the company has publicly acknowledged its existence.
Google notes that so far, Bouncer has reduced the number of malware downloads between the first and second half of 2011 by 40%.
Bouncer looks for known malware, spyware and trojans, but also look for, what Google calls, "behaviors that indicate an application might be misbehaving, and compares it against previously analyzed apps to detect possible red flags." In addition, Google also looks at new developer accounts to ensure that those we were banned once can't just come back under a different name and upload another piece of potentially dangerous software.