I'm with the others that this is a bit of a letdown (although hopefully the actual online experience is still cool.) For the life of me I can't figure out why the network settings are saved in the cartridge and not the DS. Nintendo knew from the start that they would have to save network settings _somewhere_ - whatever price savings they gained by not reserving space on the DS, they lose several times over for every cartridge now. It's even more head-scratching than removing the headphone jack from the GBASP.
The dongle marketing is interesting, but again - the PSP already has support for AOSS in firmware 2.00 and it saves network settings on the PSP. With the PSP you only have to set up to connect to a dongle once per computer and your settings are saved; in that way it's a better dongle client than the DS, since with the DS every time you buy a new game you and all your friends have to go through the 15-30 second AOSS negotiation each before you can go online (I don't know if Nintendo's vesion of the Buffalo dongle will block PSP traffic though.)
In any case, Buffalo's dongle and AOSS has its ups and downs - it can really screw up the computer you are using it on and actually disconnect it from the network, since it has to install networking drivers. For example
http://www.tomsnetworking.com/Sections-article126-page6.php:
"But the biggest problem for both AOSS and SES is that they don't play well
if you attempt to use them in computers that already have Broadcom-based adapters
installed. In the case of Buffalo's AOSS client adpater, we tested the latest
drivers on three laptops, and discovered that they will wreak havoc with pre-exisiting
Broadcom drivers. On one laptop, the Buffalo driver disabled the built-in Ethernet
(!) driver and Broadcom WLAN adapter. These problems were resolved by going
into Device Manager and re-enabling the disabled drivers."