The Google Webmaster Central Blog announced new warning notifications that are now being displayed to Google Sitemaps with minor problems.
Previously, Google showed any problem, be it large or small, as an error. Now small issues that are "confusing or inaccurate" are considered "warnings" and large issues that render your Sitemap unreadable are considered "errors."
We have more discussion and comments from Vanessa Fox at Sphinn.
In addition to this update, I reported at Search Engine Roundtable of a new Google Webmaster Link Tool July 2007 Update.Google, Google Sitemaps, Google Webmaster Central, Warnings, New Feature, Web Analytics
Source:→ SEL Blog