The images, taken at the Belmont Stakes race in New York last week, have prompted furious debate online, with bloggers desperately trying to work out if Mrs Palin has gone under the knife.
Wonkette first noticed the alleged surgical augmentation, but several more sightings followed.
"We can report with confidence that at least two people with experience in having breasts say that Sarah Palin sure looks like she was trotting out some new work at the horse races on Sunday," the website reported.
Gawker also remarked that the former vice presidential candidate was looking bustier than usual, but cautioned that "detailed analysis reveals that, from some angles at the Belmont, the breasts didn't look quite so huge."
The website suggested that Ms Palin's attire was probably to blame.
"Sarah usually favors structured, bust-hiding jackets (probably to avoid this very situation) so it's possible that we're just not used to seeing her clingy shirts. If her chest has increased in size since '08, my best guess is that it's no more than a single-cup amplification."
Mrs Palin has not commented.
She was at the Belmont Stakes to watch her racehorse, First Dude, compete.
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