The basic idea:
A patch of ecosystem would have a more limited plant selection(right now the only two forest types are forest and swamp)
Like ecosystem 1. would have tree type b. and d. and e. plant type a. f. k. o. or or z. Simply so far right?
Secondly instead of random placement of plants so all types are spread out. These tree and plant types would clump together. Small clumps,medium clump, and big clumps but almost always clumps(trees allowed more spacing in there clumping then plants) clumps would be most dense in the middle and radiate out(though not necessarily perfectly round)
Plants would have tendencies of location. Like bullrushes would be likely placed around bodies of water. Mushrooms might be most likely to be placed by certain kinds of trees. Or things unlikely to be placed by certain other things.
Ecosystems might not even contain trees at all.
A prairie ecosystem would have a selection of tall plants and wildflowers for placement. Most crusual is few areas would use regular grass since it looks so very stupid all over the place. Instead mostly tall coarse grass.
Even perhaps pools of water generated in certain ecosystems. Like alot in swamps and some in certain kinds of forests. Pools perhaps you can even walk though. (could use the gimp of one kind of tile and make it look like water.. or something like that)
Then you could just paint the map with different color coded ecosystems and automatically have a nice detailed world people can get into.
So... am I out there or what?

Anyone know of a program that can get close to doing this or able to program something like this?