I've been an avid user of Lightroom since the very first 1.0 beta and for as long as I've remembered I've wished that there was a tab on the top called "Map" that would allow me to add geographic coordinates to my photos. I didn't get it in 2.0. I didn't get it in 3.0. I had pretty much given up, and then look at what is in the brand-new-just-announced Lightroom 4.0 beta! Maps!
So awesome! Now I just need to drag 65,117 photos onto a map. :-) Lightroom 4.0 looks like a great upgrade. The only big feature on my wish list that is still completely absent is face recognition. Maybe 5.0!