@ED2 - Actually, you can sell any program you made with code from or licensed under the GPL. The only requirement is that you make the source code available with a license that grants the same freedoms (a lot of other FOSS licenses are compatible with the GPL). Nintendo could up an take Dolphin's code, throw a bunch of money and devs (not too much though, the Dolphin team has already done a great job

) and sell it outright to the public, as long as they published or made available at request the source code.
@noah - Legally in the US, from what I understand (the court cases mentioned by MaJoR), emulators themselves as programs are 100% legal to use. There's a strong legal precedent for that. Nintendo would rather you be ignorant and willing to do as they say. Hey, they
are a company motivated by profits. Both dumping games and emulation itself are covered under Fair Use. Canadians have long had the right to do format transfers as well. I was going to do a write-up for my blog about this, picking apart Nintendo's arguments one-by-one. Maybe I'll do that some time soon.
The only real concern applies to the ill-conceived DMCA, specifically the part about digital "locks" and circumvention, sometimes refered to as DRM. This is what stops software like libdvdcss (for decryting DVDs) and the act of unlocking your cellphone illegal. Essentially, given the broad language unfortunately used in the DMCA, if you have to decrypt your game , then you're probably running afoul of the law. AFAIK, this isn't an issue with Wii or GC games (WADs maybe?). I believe DS games can be encrypted, and a number of PSX games with anti-piracy technology were released as well, although they would have had to be published before October 28, 1998 for the DMCA's DRM section to apply. The PSP is the only other system I can think of that you can emulate whose encrypted games would fall under the DMCA. Nevertheless, no one gives a flying f***, neither the companies making the games (they don't sue), nor everyday gamers (they don't get sued). The DRM section of the DMCA is widely ignored (know someone who unlocked a phone?) and out of touch with our modern society. There's talk of reviewing it; there's hope for a modicum of sanity at least.
So in conclusion, the legal logic behind that page you linked to is laughably inaccurate. I love Nintendo and the games they make, but I know FUD when I see it. The end of the matter is that you shouldn't worry. Time will vindicate the emulation scene anyway :p
@SS - I would imagine that Nintendo will have to detach themselves from their own hardware in order for them to make software on other platforms. One could argue that other companies do it just fine. Look at Capcom; they've published numerous games on consoles and PCs (Mega Man, Resident Evil, Street Fighter too iirc). But it probably has to do a lot with Nintendo's brand and identity in their own hardware. Sony doesn't just make Playstations; they're known for other things (electronics). Microsoft doesn't just make Xboxes; they're known for other things as well (some obscure OS, various software). Nintendo just makes consoles, handhelds, and games (they don't make hanafuna cards like they used to

). They're probably not willing, as a company, to dilute that bit of their identity.
Not just yet anyway

Times change; we all know that. Super Smash Bros. online play would be wicked if you could host your own servers and games, rather than Nintendo's own proprietary network. The online life of games would be extended well in decades for some of the most popular games. There are still people willing to play Melee and Double Dash via Dolphin's netplay.