Get user speed through GPS

Hi all,

I've done a good share of searching on this, but have not been able to find a satisfactory answer...

I'd like to know, first of all, if it is possible to precisely get the users speed through the device GPS (don't thing accelerometer can handle that properly, right?).

If so, how? What is the "state of the art" technology for this one? Is that even possible?

All sorts of help are much appreciated.

Thanks in advance,
Klein