Ask HN: development for GPS?

With the surge of cell phone apps for iphone, android, palm pre, there are a lot of different things that you can do, but require an accurate location.

Before starting the actual development for an Android app, I assumed that GPS is reliable and fast. I have since found out that there are major issues to get an accurate location (like it usually takes a minute or two to find the first location, and in certain places it doesn't work that well).

I've read the explanation for how gps is supposed to work, but is there a good manual for how it works in the wild? Stuff I'm curious about:

- how do you increase the accuracy, decrease the time? trade offs between constant polling / battery life, etc. - how do AGPS, differential GPS, enhanced GPS, and other assistive GPS technologies compare, (including cost, if necessary) - what are the alternatives, and how well they work (is it possible to do triangulation from cell phone towers?), use wifi information?