In our various GeoClue presentations we've been arguing that location comes in many flavors, of which GPS is only one. In many cases cell tower position or even WiFi connection can provide quite "good enough" location. On Mozilla Hacks they write about an OpenStreetMap-based browser location demo. I'd say the results are quite convincing:
This is just a gentle reminder to allow other location sources that just GPS. By using GeoClue you get that for free.