Ok here is what has worked for me thus far (without any patches.)
Nintendo Wi-Fi Connection:
Play with Friend(s) - Haven't added anybody yet to be able to check.
Free Play - Working
Play Alone - Working
DS Wireless Play:
Form Party - Unable to check until my wife's AK2i arrives
Join Party -...
I don't think that's accurate. I didn't patch my Bahamut release version and I just got done playing in Free Play mode with others online as well as Play Alone mode.
The DSi can connect to WPA but PS0 won't use that connection unfortunately (at least I can't find a way to do it.) So I had to use a second router as an access point and use WEP, then I was able to get online no problem.