Here are some of those reports:
Yesterday and for the last few months the Keywords section in google webmaster tools had keywords listed, now today it says "No Data Available".
The GWT shows no keywords... any idea why?
Google confirmed the bug in these threads. Googler Jonathan Simon said in a couple threads:
There was an issue with the Keywords data that prevented it from being displayed properly for some sites. This issue should be resolved shortly. Please stand by...
There was an issue that caused the Keywords data to disappear for some sites. It should be resolved shortly. This issue was isolated to the Keywords report in Webmaster Tools and is not related to your site's performance in the search results.
And Googler, JohnMu said:
It does look like something got stuck there on our side. This does not have any impact on your site's crawling, indexing or ranking, it is only the display in Webmaster Tools. It should be back to normal in a few hours, we apologize for the inconvenience.
It looks like something got stuck on our side there, sorry! The keywords information should be back in a little bit! Thanks for posting!
It seems to be back now, if you still have issues, take them to the forums.