It has to be more than good looks or a good body. After the recent debacles of movies like Catwoman and Electra, the comic movie genre needs to treat this character with the respect she deserves.
DC did an excellent (excellent!) job with Batman in Batman Begins. The character was shown as he is, not as the schlock presented in the last few Batman movies. The need to do the same with Wonder Woman.
Remember that Wonder Woman is a princess on her home island of Themyscira (Paradise Island to tv watchers). She's 5' 11" and weighs 140 lbs. Her physical might has allowed her to go against Superman before.
At the same time, she has poise and dignity. She is the very model of the ultimate female superhero.
Sandra Bullock *has not* been confirmed as of this post. That is all rumor. Although Charisma comes closer to the look than many, I don't think she'll be WW due largely to Joss not wanting to cast his Buffy/Angel ppl (same for Eliza Dushku).
Although there are a few people who would be interesting, such as Monica Belluci (Wonder Woman is essentially Greek and Monica, though Italian, has that look) or Angelina Jolie (simply because she's very physical looking though too associated with Lara Croft), I don't think any of them will do. I think Joss will pick a complete or relative unknown. This would be his best option.
Don't underestimate Joss. His writing is absolutely superb. Many associate him only with Buffy/Angel. However he has shown he can pick up the reigns of writing The X-Men comic flawlessly. He is completely in touch with who those characters are. You can see elements of his writing style present but they are in no way just another version of Buffy's gang.
His directing on Serenity is awesome, creating one of the best sci-fi movies in years. Too bad Lucas didn't have that talent when he mutilated his franchise with The Phantom Menace!
I feel Wonder Woman, along with Superman Returns (directed by X-Men director Bryan Singer) will be a critical juncture for the comic book movie genre. However, I also believe that both directors can do it right.
I see her on some eye care commercial every now and then. Of course Linda Carter didn't have that lean, wirey look that is so popular now-a-days, so I doubt whoever they pick will be as curvy as she was. I guess it is all relative anyway. 
Darn, I am getting old! 
