The N95 has a native app called Maps (Smart2Go). This uses maps which are resident on your phone and can be downloaded to your pc for transfer. There is no need for a data or inetrnet connection to your phone when using the Map app, only when you want to get turn-by-turn guidance. Currently the NZ map is poorly detailed and TBT is not available, maybe next year this may improve.
Google Maps in a map-browser, it has no GPS functionality ie it cannot tell you where you are, it just displays maps on your phone, these have to be downloaded as "tiles" over the net and incur data charges!
Mobile Google Maps Or MGMAps is a freeware project that currently uses a perl script to download 100's or 1000's of "tiles" from Google Maps and store them on your phone. The app, which is free, uses the N95 in-built GPS receiver and calls up the needed map tile from your phone as required. You do have to put a bit of work in getting the map tiles but once you have done it, it's like riding a bike! However, the big issue is that currently, MGMaps is causing big problems with memory usage on the N95 and until Christien can find the answer, really MGMaps is not an option.
SmartcomGPS is a commercial product ($40US I think) that works with the N95 internal gps unit. It has voice guidance, map rotation and lots of other features but you have to make or obtain your own maps using a range of software. At first I found the procedure quite daunting but now its a piece of cake. This is the only piece of GPS software that has given me the ability to get turn-by-turn navigation and detailed NZ maps. You need to be comfy with things like Photoshop or at least stitching image files together as well as basic GPS issues. If anyone is serious about using this product I am happy to help.
SportsTracker is not a mapping app, it has some other nice features but is not going to help you with navigation.