This is an Android Market security update that undoes exploits caused by the malicious applications that were removed from Android Market on 03/01/2011. Only some users were affected. Those users received an email notification that states this update will be automatically pushed to their devices. This app will be removed automatically after it has completed running. There is no need to download and install this application on your own. Still you can download this app and use it to scan your mobile for virus.