GPS on Iphone?

It will work, but unless you use it only on wifi, you're going to rack up a monster bill for data usage.

iPhone GPS works fine in Europe. It does not logically follow that a "monster" bill results from using it. If you educate yourself on data usage, you can avoid big bills. Downloading maps is a big data hog, but occasional use can fit within a reasonably priced data roaming plan. Some apps, such as Michelin Restaurants and TomTom GPS, utilize the GPS function without requiring any data feed.

I can speak directly to this issue. Last August/September my wife and I went to Europe for 36 days. I did everything I possibly could beforehand to plan for using our two iPhone 4 phones while there without racking up huge bills. I knew that I would be utilizing free wi-fi as much as possible but figured there'd be a few occasions when it would be nice to have data available. So, I signed up for the 20 MB Data Global Add-On for $24.99. I reset my usage tracker and monitored things like a hawk. About 21 days into the trip, I was still under my limit (I had used about 15 MB of my 20 MB), then we got lost on foot trying to find our hotel in Florence, so I turned on the data to use Google Maps GPS to locate where I was. I had it turned on for about 5 minutes. When I checked my usage a little while later, to my surprise, I had gone over my 20 MB limit. Fearing that I'd get stuck with big overage charges, I immediately changed my data plan to the 50 MB Global Add-On for $59.99. AT&T pro-rated the my bill for the time I was on the lower plan and higher plans. I had decided against the 50 MB plan initially because it wasn't as good of a value and I didn't want to spend money on something I might not use. So, beware of how intensive GPS usage on Google Maps can be. As another poster wrote, it really is a "hog."

What would work equally well is to get a free map from the TI and wrap it around your I-whatever with a rubber band. Optionally, you can just hold the map in your paw. I've been screwed up in a lot of places, but just asking for directions in the nearest store, bar, or bawdy house got me going again. People are pretty nice.

Thanks everyone! its good to know how I can use my gps, I will probably go for the 50 mb plan just to be on the safe side

My daughter ran up a $600 bill on her iPhone on her honeymoon to Italy 3 years ago, so I know that monster bills are possible. I reset my iPhone earlier today, then dropped a location pin on Google Earth while on 3G. When I checked my data use, it was 5MB! If I had been paying $60 for a 50 MB plan, I would have spend $6 for that map! For my trip to Italy next month, I'm taking my iPhone, which I'll leave on airplane mode except when I'm in a wi-fi hotspot. I'll turn it on for emergencies.
For maps, I'll use my wife's iPad, which is wi-fi only, to load the day's locations before we leave out. I've discovered that it retains quite a bit of data in Google Earth. (I guess I could ask directions, but I'm a a guy, so nahhhhh)

There are also map apps for the iphone that let you download your data ahead of time and do not require internet or 3g access to use them. There are a few so checking them out ahead of time may be worthwhile. We found GPS in larger cities to be hit and miss because of buildings blocking signals (we took a small Garmin GPS for driving in Tuscany and tested it out in Venice and Rome, would lose signal in many places and it would catch up to us again when we got into the more open areas). Our favorite thing to do for most cities is to have a foldable map (I like the Streetwise ones) for reference and then look up which way we need to go and then put the map away and take the actual route that looks most interesting as we wander in the general direction.