I think everyone here seems to be confusing what "NTSC" and "PAL" are.
NTSC and PAL are color encodings. By themselves, they have nothing to do with video timing, only how the color subcarrier is encoded. Remove it, and you get a black and white picture.
"480i" and "576i" are defined video timings that specify how many lines per frame and how many frames per second are drawn. Usually, NTSC is paired with 480i, and PAL is paired with 576i. It is entirely possible to use PAL with 480i (aka "PAL60"), and NTSC with 576i (but no one does this).
On GameCube and Wii, there's two versions of 480i: NTSC and PAL. The video timings are identical, but the NTSC version uses NTSC color encoding while the PAL version uses PAL color encoding. In addition, Nintendo decided to save some pins and overlay the S-Video and RGB functionality such that if using an NTSC mode, S-Video is enabled, but if using a PAL mode, RGB is enabled. This is why SCART users end up with a red-tinted screen when running an NTSC game unless they force a PAL video mode.
Finally, there's 480p and 576p. These don't work with NTSC or PAL encodings at all; they're only supported on GameCube and Wii if you use the component cables. Hence, there is no "NTSC" 480p or "PAL" 480p.