The security situation on Android looks more and more like the security situation in Windows. This is the opinion of the security experts at Kaspersky in their Malware report for the first quarter of 2011. They expand on that comparison, first noting that there is already a "plethora of Android devices" with outdated software and that this software can contain unpatched vulnerabilities.
Kaspersky: Android is the new Windows - The H Security: News and Features
Kaspersky: Android is the new Windows - The H Security: News and Features