Repost ;-) In the Twitter world we use Retweet if you post the tweet of someone else. So why not do it with blogposts ;-) That way you can easy filter on subject.
My colleague Daniele Muscetta has posted an great article about using PowerShell to Check for updates in OpsMgr 2007 R2. I wish had found out how to do this, but you can learn a lot from this article.
Remember that this is just SAMPLE code, it is not meant to be used in production environment and it is worth mentioning again that OpsMgr2007 R2 this is BETA software at the time of writing, therefore this functionality (and its implementation) might change at any time, and the script will break. Also, at present, the MP Catalog web service still returns slightly older MP versions and it is not yet kept in sync and updated with MP Releases, but it will be ready and with complete/updated content by the time R2 gets released.