No, because it insists on using A-GPS to get the initial GPS lock so it NEEDS the Internet, stupidly. I also believe it still has to use the Internet to do route planning, unless you manually insert the start/end points. Although personally I find the Maps application so confusing to use that I have never properly used it anyway.

As for Map Loader, I gave up and used the manual method downloading the ZIP and extracting it in cities, seems to work fine. Ironically it looks like I had already done this before and it possibly was already using the cached maps, I had just forgotten as I don't think it worked when I did it back then on the original N900 firmware.