This article seems to have alot of jagger update summary in one place. The last two sentences are a fairly interesting summary:
While not perfect this update has done a lot to address a number of serious issues with Google's results.To be certain, there is still room for improvement in cleaning out sp@m results however they are definitely moving in the right direction. But what does this mean for us?
For those seeking high rankings on Google this update and the direction it predicts for future updates indicates that clean tactics will be necessary.Sp@m is becoming less-and-less effective and it's detection is becoming stronger and stronger (though certainly not perfect at this point).Building solid, natural links and creating a site with a lot of useful, relevant information will win out in the end though the aging delays on both domains and links mean you will have to be dedicated to the task.And this is the environment Google is hoping to attain, dedicated webmasters creating larger, more relevant sites with natural links. Mission accomplished.