Right now, nothing.
Yes yes, there are some programs that use it, as you mentioned. But as you noticed, no one cares.
But it's still a cool feature, and eventually people will make use of it. I imagine a future version of iPhoto (and other photo organizers) will make great use of this. I'm sure you'll be able to bring up a map and scan through your photos by location...kind of like a big personal google-earth of your life.
So yeah, that probably won't come out as a feature until 2010 or 2011. Won't it be great to load that upgrade and see all of your photos for the past 3 or 4 years appear on such a map?
Or how about typing "San Diego" into Spotlight and having your computer show you all the photos you took there, even though you never named, tagged, or key-worded them? Pretty cool.
Trust me, it will be worth it some day. Just not yet.