First the good news: there is new summary report for Wikimedia page views that presents trends for nearly all projects on a single page.
Now the bad news: a few days ago it was established that the server that collects and aggregates log data for all squids could not keep up with all incoming messages, and hence underreported page views. When I suggested that recent page view trends looked very suspicious Tim Starling and Mark Bergsma quickly analyzed the cause and fixed server overload. Kudos to them. For April – July 2010 I could still infer the amount of underreporting from available log files. Counts for these months have been corrected. For earlier months, possibly from Nov 2009 till March 2010 counts are still too low. For details on the error correction see this pdf.
Reports affected: all wikistats reports that are based on dammit.lt hourly log files are affected, notably page view reports and server request reports. The same goes for the monthly Report Card. Earlier editions of the monthly server request reports are not yet corrected like the page view trend reports (maybe just a notice will be added), and of course even though absolute numbers are too low, comparisons are not affected (e.g. market share per browser or OS) . Other sites that build on these log data will be also affected, notably stats.grok.se , trendingtopics, amaglamate.