The DSi is some kind of next-next-next-hyper-next-generation hardware. It's far too complex for the current generation of homebrew devr's, and as long as there's no DSi website/section, there won't be any progress.
The amusing aspect is that there are a lot of people claiming that they are interested in the 3DS, and, at the same time, saying that they don't want to know anything about the DSi... apparently not realizing that nobody will ever understand the 3DS hardware without first understanding the DSi hardware.
The 3dbrew people are even have this funny statement on their
http://www.3dbrew.org/wiki/3dbrew:Community_portal page:
"A forum will be created when it becomes necessary, for e.g. actual discussion about homebrew development. Currently homebrew is not possible, so a forum is not needed yet. --Neimod 01:05, 29 February 2012 (CET)"
Which sounds as if they are waiting until somebody else is reverse engineering the 3DS (and DSi) consoles on their behalf.
But, I just noticed that somebody has created
an actual 3DS dev forum a few weeks ago:
http://4dsdev.org/ and it's even including a section dedicated to reverse-engineering! That looks very interesting - I really wonder what things might happen in future!
The name "4ds" does also sound promising. It could be read as an improvement over the current 3DS scene, or read as intended FOR supplying the current (3)DS scene with tech details that they were never interested in. And, as it isn't explicitely called "3DS", there might be even some chance to get a DSi section in there.
PS. alternately, I've asked at
http://forum.gbadev.org/ a while ago, and it seems that it would be possible to create DSi and 3DS sections on that site, additionally to the existing GBA and NDS sections. That would be also nice because a homebrew-dev-forum would be generally better than a homebrew-consumer-forum like gbatemp. But in case of creating a 3DS development forum, it looks as if
http://4dsdev.org/ has won the race.