There was a thread somewhere with instructions on how to make maps arbitrarily large, so only your memory space is the limit.

Elemental is Emeralds 5

Elemental is Emeralds 6

Here are some videos that I did that involve a larger map, a 14x14. And I'm currently working on converting some video I took this morning involving setting the super map up. And will post the additional videos sometimes later tonight. You can find them at my website.

http://gorstagg.wordpress.com/

Hope that helps address it. And (The way I did it myself was start with a large blank map. Then saved it. Then went in an edited the xml file for the map and changed it's map size to bet 224 by 224, 14 x 14 tiles, and 16 by 16 squares.)

Voila, and thus I'm able to get a larger file up.

I wasn't necessarily talking about modding, I meant these controls and map sizes for the random map generator before you start a new "sandbox" game.  I don't really like the idea of making too many of my own maps because I'll know what to expect before I play on the map.

Thanks for the replies though, I think astrath anwsered my question best, though I still don't know if the large map we already have is the largest there will be.