I think that "Search My Calendars" and "Search Public Calendars" buttons are switched now, aren't they? (Also, typing the query and hitting Enter leads to results from "my calendars" now. I surely remember being annoyed after hitting Enter and seeing "Add Other Calendar" page.)

It has been reported several months ago. It is so annoying :(
Another trouble is to browse public calendars: how to go to page 2 of results? 80% of the time I browse a category of public calendars, there's only one page of result. I just can't believe there's only 10 calendars in each category.

I forgot the link:
groups.google.com/group/google ...

Thank you Matt Cutts?!?!?!?!? :-D
mattcutts.com/blog/track-your- ...

I remember criticizing the change when Google Calendar made public calendar search the default option:
googlesystem.blogspot.com/2007 ...