i've been hunting for an answer for a few hours now. i wrote to itunes customer service, which guarantees a response within 48 hours.
hopefully apple will role out artist sign-up pages soon, because so far, ping is only fun for fans of U2, yo-yo ma and lady ga ga.. weird that they wouldn't have the artist pages ready at launch. seems like a big part of what makes the idea of ping interesting.
i'm very curious as to how itunes can guarantee artists their names and verify who they belong to, etc. will post if i hear anything, of course.
by the way, zoe - you are such an incredibly gifted person and i'm a huge fan of the beautiful music you make! good luck on your ping adventures.