http://secunia.com/blog/52/ "Now available from Secunia is the BETA release of the latest PSI. Amongst the usual programs PSI scans through for needed patches, the new version will now also tout a feature called 'Secure Browsing'. The new feature informs users of what programs and plugins are integrated directly with their browsers and any security issues affecting the browsers and their plugins."
I think that Secunia's PSI fills a unique niche. Being able to see which of your packages is out of date is a valuable tool that Microsoft does not provide for non-Windows binaries. Keeping up with patches for your system binaries is important. The newest Beta version appears to be looking at your plugins for your web browser, too!