re: Check out todyas new picture from Opportunity.
HIghly unlikely to be the earth. Thats a navcam image - so FOV is around 45 degrees - and the seperation between Sun and that dot is probably around 20ish. So close after Solar Conjunction - the Earth is more likely to be 3 or 4 degrees from the sun
More likely to be a dodgy ccd pixel from a glare off internal reflection - or a bit of radiation.
Doug