Just upgraded ai1ec to 1.9.4 "free" version from 1.9.3 "free" version.
Issue one of several critical event display bugs from this upgrade:
When viewing the event listing page, the sidebar widget hover/popup text now shows all button text inline with event info (even if buttons are turned off). For example hover/popup text now shows "Back to Calendar When: February 26, 2013 @ 9:00 am – 5:00 pm Add to Calendar Add to Google Where: Advocates for Youth..."
Sidebar widget hover/popup text is correct on pages other than event listing page.