Finding meeting times could be more straightforward if users had a facility to provide a link to their availability, based on their primary calendar.
This is the complementary/opposite suggestion of http://ideas.projectplace.com/feedbacks/46589-export-of-all-meetings-in-ical-ics-format
What I propose:
Create a setting "Calendar connection" where a user can paste in a (read-only?) .ics link as provided by Outlook, Google Calendar, iCal and many other widespread calendar applications, displaying "busy" information.
Integrate/Visualize this information when seeking possible meeting times, for all users who have linked to their calendars.
If desired, PP could suggest "the next time that all participants are available for 2h".
Similar functionality is implemented by e.g. Outlook, but does not work across organizational boundaries - which is a common reality in project work.
Let me know if this requires clarification.