One of the most talked “non-features” of iPhoto ‘11 is the lack of support for calendars. A very appreciated functionality in iPhoto ‘09, Apple decided to not include it in the first release of iPhoto ‘11.
But calendars are coming back, and they’ll be available “soon” in iPhoto ‘11. As Apple writes in a support document available here:
Will I be able to create and order calendars in iPhoto ’11 in the future?
Yes. We will be adding the ability to create and order calendars in iPhoto 11, and these features will be available very soon.
When will calendars return to iPhoto ’11?
Apple is working to bring calendars back as soon as possible.
Also, Apple suggests you don’t upgrade to iPhoto ‘11 if you have a previously created calendar that still needs to be ordered:
If I have a previously created calendar that I need to order, what do I do?
Do not upgrade to iPhoto ’11 at this time. Ordering from older versions of iPhoto will continue to be supported.