Of the five cool programs packed in to iLife, my favorite is iPhoto. As I take more and more photos it becomes quite a chore to manage the pictures. iPhoto allows you to organize your photos by when they were taken, who is in the photo, or where the photos were taken. This makes finding photos of certain events like weddings, or pictures of "Billy" extremely easy to locate and organize. On top of organizing and locating your photos you can also easily share them with Facebook and Flikr now. Is it worth going from iPhoto "˜08 to iPhoto "˜09? Yes.
The look and feel, going from "˜08 to "˜09, hasn't changed much but has added an organizational pane (called Source List) which shows the Faces/Places features. The Projects areas has been renamed to Keepsakes.
Faces
The best feature, in my opinion, is the Faces feature which basically learns peoples faces, face recognition basically. This feature isn't perfect but does a pretty good job after a bit of software training. It is quite a hoot and becomes a bit addictive. The iPhoto Faces feature matches facial bits, like shape, mouth, eyes, nose, etc,
While looking through your photos you can click on the "name" icon in the toolbar to add a name or pick one from your faces database. Even if iPhoto doesn't recognize a face you can still add the proper name to the picture. The face recognition can be quite funny at times, I had it match a pattern on a tree trunk to my brothers name.
After you have a bunch of faces matched up with names, browsing by name/face is quite fun. The pictures show up on a corkboard style backdrop with a picture icon for each name. A cool feature is the ability to drag multiple faces to the album section on the source list, this automatically creates a smart album with pictures of the people you selected. Very slick.
Places
If you have a GPS enabled digital camera (or your iPhone camera for that matter) you can use the Places feature in iPhoto. The pictures are tagged with a geo location that iPhoto keeps in its database. Once enough photos have been tagged with locations you can display maps of your photos. The geo-coding data structure used by iPhoto is quite smart and will show local cities, etc,
A minor frustration with Places is that you can't "undo" if you accidentally set a location wrong. Sounds goofy, but I accidentally changed locations on an entire batch of photos and had to fix them one-by-one.