If you login to your Google Webmaster Tools account and notice that Google is reporting that they have indexed 0 of your submitted pages through Sitemaps, then don't worry - you are not alone.
A WebmasterWorld and Google Groups thread has several webmasters who have noticed the same issue. I suspect it is either already fixed or that it is impacting a select number of accounts. I personally do not see the issue when I check some of my sites.
Clicking on your Sitemaps section might show something like this now:
Sitemap stats
Total URLs: 171
Indexed URLs: 0
Total URLs would be the number of URLs submitted to Google via Sitemaps. So yours may be larger or smaller.
Is this still an issue for you?
Forum discussion at WebmasterWorld and Google Groups.
