It no longer tosses out the wagon and other aspects of the site if you didn't dig -- since the maps are now completely determined by persistent seeds, using the start site again would just make the same map without the old wagon, so the old wagon might as well be left there. So you can 'reclaim' even if you abandon immediately. That's exploitable, but no more exploitable than it currently is.
You are still limited to the map you see there -- this is just a space/speed constraint now though, rather than a problem with how it is stored. If people want to play fortress on larger maps eventually, it won't take so long to add. It would also be possible to start your map smaller and just let you extend in the direction you want to extend, out to some limit determined by your system. For now, it's 480x480 like it was before. You can walk around the whole mountain range as an adventurer without walking off 'an edge' (or die of hunger trying anyway), and you'll find the fortress waiting there for you when you get back. There is still an edge at the N/S/E/W ends of the world. It just blocks your movement (I think).
I also did play now! at an old site with an adventurer today, and then wandered far south until the map offloaded, found a landmark (a frozen pool with 3 willow) and then walked back to the site and returned the axe I had taken from the wagon. Then I went back to the landmark. So that seems to be working. There's an issue with the wilderness of course -- saving changes you make (like lighting a forest fire) isn't going to be possible in all situations because there's just too much of it. All important locations are still saved square by square, and the rest will be fudged bit by bit (but not now).
The wagons are dropped as close to the center of the map as it can place you. That's just a convenience for me now. Currently, you can then walk where you want and dig an entrance, and then use the new gate-changing feature to make everything respect that. There might be some exploits that arise from positioning the gate somewhere strange to eliminate unwanted migrants etc., but for now it works this way.
As it currently stands, any edge will work for the road -- if you connect any map edge to your depot, you are fine. I don't think it lets you dig out the edges, so you (probably) can't do something like send a road through the interior of the mountain. No doubt there will be lots of things I missed though, and we'll just deal with them as they arise. Or put them on the to-do list, anyway.
[ March 15, 2007: Message edited by: Toady One ]