At the moment it is possible to let all stat data be evaluated for a certain date, week or year.
However I would regard it as highly desireable to not just filter by timespan but also by page sections (f.i. Linux, Environment, Index Page, Greenhouse Effect, ...) for all plugins. Page sections should thereby be defined by a set of URLs as they can be found in the piwik_log_action table.
This is to my mind what Piwik is really missing towards Google Analytics. I am planning to use Piwik instead of Google Analytics but would thereby really desire this feature!