I own a Fuji X10 and I'm actually more disapointed in it's low light AF performance than in the orbs.
Today I shot a picture of ice parts on our gardenpond. I've experienced orbs and one orb even had an extra bright blue circle around it.
Shot at 1/160th, 28,4 focal length. I can't find the ISO on the Mac and I already erased the original from the SD card., but is was ISO 400 or lower. It was shot in P-mode.
I'm going to check with the shop where I bought my X10. I'm seriously thinking of returning it and look around for a replacement.Low light AF is also below expectation. Even taking handheld outdoor pictures in wintery overcast conditions was very hard to do. I don't really know why this camera is supposed to be good in low light conditions. I really hope I have a bad example because I really like its looks and way of operating. But it hasn't convinced me picture wise.
I could call myself a Fuji fan, but with this kind of quality it's not possible to call myself a fan.
Edit: Firmware 1.03