So, yea, lately there's been a lot of talk about how big the San An map really is. Not to mention plenty of people posting absurd comparison maps on message boards all around the intrawebnet. You know, the ones with like fifteen Vice Cities placed end-to-end across the map. Maps which, after doing the math, would end up with cars in the Vice City overlays being about the size of toy Matchbox cars in contrast to San Andreas.
It is into this melee of theoretical cartography I now enter in hopes putting idle speculation, rants, and worries to bed...
Right, so, if you look at the official site, navigate into any of the various districts around the map, and mouseover a point-of-interest. The location name, time, and some coordinates should then pop up on the top left of the Flash movie. If one was to take these very coordinates, locate them within (or in some cases outside of) Vice City's game world using a 3D map editor, then scale the known San Andreas map to match, the results would look something like this:
Without boring everyone to death with details about bilinear pixel resizing, 3D world-space bounding boxes, and area triangulation equations in Euclidian geometry, I can say that, within a margin of error of less than 2%, that this overlay map is dead-on given the array of coordinates at my disposal.
The only question that remains really, is whether or not the cooridinates on the Flash map are in fact from the game, or just something the web design team at Rockstar threw in for fun. Judging by the width of the streets on the maps, it would appear the coord's are correct. For if the numbers were something collectively pulled out of thin air by the web team, the chances of them scaling this closely would be quite negligible. Mind you, this map comparison has not been confirmed by Rockstar, and is only based on my knowleged earned from years of experience modding the GTA series.