As you already know from my coverage Google has updated Google Sitemaps to include many new features I discussed at SEW blog including;

+ New verification method
+ Indexing snapshot
+ Notification of violations of the webmaster guidelines
+ Reinclusion request form
+ Spam report
+ New webmaster help center
+ More about our new look
+ Adding a Sitemap
+ Navigating the tabs

But the main change, for Webmasters, in my opinion, is Google notifying webmasters of penalties as Matt Cutts describes it. They don't necessarily tell you, hey - your site is kicked out of the Google index because you did X, Y and Z. Plus Google doesn't necessarily tell you that you have no pages indexed, it tells only "some" webmasters. They have a message that reads;

No pages from your site are currently included in Google's index due to violations of the webmaster guidelines. Please review our webmaster guidelines and modify your site so that it meets those guidelines. Once your site meets our guidelines, you can request reinclusion and we''ll evaluate your site. [?]
Submit a reinclusion request

Many Webmasters are happy about this and discussing it in the various forums. Two forum threads I found discussing it include; DigitalPoint Forums & Cre8asite Forums.