mobile phones - anyone know about sat nav / GPS?

[notanickname]

A question for those more technically advanced than me!!
I'm thinking of upgrading my phone and was tempted by having Sat Nav thing, which I think is called GPS?? Just wondered if anyone has this and how it works - ie do you need to buy any additional software or does it cost you extra to use it? Or do you have to be on a special sort of tarriff?
And... is it any good?
Thanks for any advice!

I have a Nokia N95 which has built in sat-nav. All the software is pre loaded and it is free to view the maps and plan a route but the voice guidance requires a subscription of £50 per year. AFAIK you don't need any sort of tarrif and I would imagine that you would get the same features on PAYG, though it sometimes gets data by GPRS so there may be a cost involved there.

The mapping is quite clear, easy to use and much like a proper sat-nav. The main problem I have found though is getting a GPS signal can sometimes be very difficult, especially in bad weather.

There is a new phone out, the N96, which I don't know much about but would assume it has the same sort of thing.

HTH

Ditto supportman - DP has a N95 and we use the GPS for geocaching - signal a bit iffy in bad weather or under trees (obviously) but easy to use and in our case was a bit of a bonus really.

Thanks for the replies, that's helpful.
I'll just try to get my head round phones and tarriffs! Maybe one day we'll all have sat-nav or maps as standard.