I think John Mayer was underrepresented with Grammy wins. Not to take away from Norah at all but he writes way more of his music. Norah only wrote 2 1/2 songs on that record.
But I don't think she is a flash in the pan by any means. Her father is Ravi Shankaar, so she has talent in spades. Her piano solo on "Don't know why" is brilliant. It is very simple, and compliments the tune perfectly. A lot of Jazz musicians don't know how to play such lyrical and sparse phrases.
As for Diana using her looks to sell out, I doubt she could have done that, but I don't think it hurts her career either.
She's a pretty darn good pianist as it is and that take Years and Years of practice. She would become ill playing silly smooth jazz licks and other Kenny G like fluff. As for Kenny, he used to be a legit straight ahead jazz musician until he got tired of practicing 8 hours a day and playing gigs for 50 bucks. Ever wonder why Starbucks is so Jazz conscious?
I like Norah very much, but I wouldn't call her a 'jazz' musician. Unless there is something I haven't heard of hers, she is definitely a 'pop' musician more. Let me reiterate, "pop is not a dirty word". Pop music can be very broad. It can be anything it wants to be, you don't have to follow a tradition. She uses Jazz instrumentation and includes Brian Blade on her record, so I don't really care if you want to call it Jazz, i'm just saying. . .