What exactly does this “palm tree” icon under “Recent” in iPhoto (9.6.1) represent? Is there a way to disable it?
After posting the original question—and noticing the same palm tree icon appears at the top of the sidebar list under “Library” under the name “Events”—I experimented and it seems that the the listing under “Recent” represents the last batch of event photos you have viewed. Very odd feature if you ask me.