We reported a month or so ago that Google News said the sitemap index count is not accurate for determining how many of your articles are indexed by Google News.
Google, in the case of Google News, recommends you do a site command, to see which articles are indexed. This is the opposite for normal web search. For web search, the more accurate way is to use Sitemaps indexed count in Google Webmaster Tools.
That being said, Google's Stacie Chan said in a Google+ hangout at the 42 minute mark that they are talking to John Mueller and the Webmaster team to make that count in Webmaster Tools more accurate.
Here is the transcript:
Ah, so that is the indexed count of the articles. A lot of publishers do ask about that so I am glad you asked that.So that count, indexed count, that you see in Webmaster Tools isn’t always the most accurate number of the articles that we’ve indexed from your sitemap. A lot of time I just tell publishers to do a site command search. That’s the most accurate way, you see the articles directly there on your screen, which ones were indexed in Google News.
And John and I and the Webmaster team have actually been talking a lot about this and we are trying to look into updating this number more regularly.
Here is the video:
Forum discussion at Google+.