I had an issue with my wordpress blog with the google indexing after posted an article . When I first started my blog my posts where getting index within minutes. But last week none of my posts ware getting indexed.
I looked at my google webmaster tools and at the starting of the month I had a number of pages that were getting crawled. Now it’s way down. someday I didn’t even get a bot on my site. I had changed nothing. At last I checked my robots.txt file. It was changed to
User-agent: *
Disallow: /
I didn’t have any idea on this changed automatically!!. I edited this into
User-agent: *
Allow: /
And checked the google after a new article posted. Now the issue is fixed and the google is indexing my posts successfully.
October 27th, 2009 
thx you!! My case also