A Google Groups thread shows numerous complaints from Google Webmaster Tool users who say that they have not received any updated query statistics since the beginning of April.
The only information that is seemingly updated is the sitemaps and last crawl data.
My site is regulary being indexed, but no updates at all to the search statistics or external links section...
Jonathan Simon of Google has updated the thread with information informing the community that they are working on getting the data updated for all affected users:
Thanks to all for reporting this issue. Our engineers are currently working on getting the Query Stats in Webmaster Tools updated. We expect to have the latest data available by the end of the week.
Forum discussion continues at Google Groups.