It would be nice to see more video conferencing solutions integrated. We use whereby.com for example. In our case we'd just need a link to be added to the location of an event.
Having contact lists display a list of rules that they're included in would be very helpful for keeping track of which contacts will be affected by different rules.
Ability to toggle month view as the default for the calendar
Setting Front Calendar to the default view should make it stick so that every time user opens the calendar it will show the month view instead of weekly