Before everyone starts hating or whatever, I'm just posting this link because I used love DotA (stopped playing because of WoW) and now that SC2 is out I'm back into the RTS genre again (and hence custom maps)
Anyway, its technically not DotA, AFAIK the DotA guys have no plans to make a SC2 map at the moment. It's called
Storm of the Imperial Sanctum (SotIS) and you can pull it down off the multiplayer section of SC2.
The map layout is pretty much exactly the same as DotA (with 'hidden' vendors and all) only 10 heroes last I checked and frankly speaking some seem slightly OP, but its a new map, lots of time to fine tune it.
It won't be as popular as DotA, not as well balanced as LoL/HoN and without proper LAN support in SC2 many won't find SotIS LAN weekends as appealing as War3/DotA weekends used to be.
That said I'll still be playing it with my friends, loading a map in SC2 is far easier than having to keep LoL up to date and having all my casual gaming friends register/install/etc.
