http://www.drastic-ds.com/viewtopic.php?f=5&t=2498 -- other posts on wifi
http://www.drastic-ds.com/viewtopic.php?f=5&t=2412 -- ditto
http://www.drastic-ds.com/viewtopic.php?f=5&t=2352 -- exo explains it all (sort of)
http://www.drastic-ds.com/viewtopic.php?f=5&t=2 -- faq
This was 5 mins of searching on the same forum as this post. Here are the issues with wifi in drastic currently.
1.) Nintendo uses odd hardware -- Noone has emulated Nintendo's own wifi chips perfectly yet.
2.) Homebrew servers are designed to be used with real hardware see point 1. -- you could modify the hombrew servers to optimize them for emulated systems but until that is done it is no easier then nintendo's own.
3.) Nintendo in an attempt to make online kid friendly/ less parent scary made the most esoteric and asinine implementation of ad-hoc and infrastructure connections seen in the world of consumer consoles (yes I am including sega net, for the genesis).
I am not saying drastic will never have wifi connections, only Exo knows for sure. But until there is news along one of those lines it will be more then an Update needed.