iOS-Inspired iPhoto for Mac Update Coming This Summer?
The report includes a couple of details about potential new features. The new Mac version of iPhoto is said to gain the excellent iPhoto Journals feature and a redesigned photo retouching system, both inspired by the iOS version of iPhoto. The site also claims that the new iPhoto will require OS X Lion or Mountain Lion -- Snow Leopard won't be supported.
Apple Weetjes doesn't have much of a track record on rumors, but the features they mention do seem likely to make their way to the Mac version of iPhoto at some point.