I've received dozens of emails, tweets and social messages about Google Webmaster Tools having a delay in their reports.
It is true, there is a large thread about it over at Google Webmaster Help where Google confirms the issue.
The reports seem to have not been updated since August 28th/29th.
Last night, Googler Jonathan Simon confirmed the issue and said it will be fixed soon. He said:
Thanks to everyone for reporting this issue. You should see more recent data for search queries in Webmaster Tools within the next day or so.
Googler JohnMu added:
Just a short additional note -- the issue we're resolving is the reporting in Webmaster Tools. If you are seeing changes in the search results or with traffic to your site, then these changes will not be related to this. If you're unsure of what might be causing those changes, then I'd recommend starting a thread with your site's URL (use a URL shortener if you prefer), detailing the issues you're seeing, and any changes that you might have made recently.
Sometimes it seems that things are related, when they're actually just happening at the same time :-). If you're only checking for traffic in Webmaster Tools, it would probably make sense to wait a bit until the data there has refreshed (or better, cross-check with either your site's analytics tool or the server logs).
I can confirm the issue on my reports as well but I am not personally worried.
Forum discussion at Google Webmaster Help.