Over the last few days we've been spending some time on an RSS feed generator which can help you stay on top of new IOS releases. It takes regular expressions as input and can be useful for a quick search or generating an RSS feed for your favorite news reader.
The database is built upon a public md5 database Cisco publishes roughly every week. I cannot vouch for the accuracy of this information.
You can find the quick search & rss generator at http://snijders-it.nl/ios-rss/.