Gisele does not have fake breasts.
You can spot fakes very easily by the fact they have a slight corve on top, where they'd normally have a teardrop appearance. Neihere Gisele nor Heidi have that. Heidi's, in fact, are exceptionally tear dropped (at least in that famous photo of her caught on a beach sunbathing topless). You can't fake the teardrop.
The chick who is utterly amzing is that fair skinned, sorta freckly all American girl looking chick (even though I think she'd from NZealand) in the Vic Secret and J Crew catalogues. Those are real, and they are unbeliveable. Her body is simply astounding, and her face is great as well.