since they cant "lie" about it because of ebays policys, (not saying they didnt, but they shouldnt have) it is most likely a camera with an interpolated algorithm, here is a good explanation from
http://www.steves-digicams.com:
-="Interpolated - Software programs can enlarge image resolution beyond the actual resolution by adding extra pixels using complex mathematic calculations."=-
basicly, it guess what the color of the pixel is most likely to be, ex: if two blue pixels are next to each other, the one between are most likely blue too.
so, it may be technicly 10 mp, but the image quality will not be as good as a "real" 10 mp camera, also, the sensor is CMOS, which at this time, usally has incorrect colors and probly wont work well in low light condtions. it may work well for just snap shots, but if you are a photographer, it wont be as good as a good $800-$1000 dollar camera.