What camera did you use? I came across an article on the web before saying that these are random "lighted dust" spots, from out of focus dust particles that are hovering in front of your lens when you took the picture. Can't seem to find the link now but will post it up if I do find it.
The same phenomenon affected the first digicam I owned too, a Canon Powershot S10. I have yet to experience the same with the G3 and EOS 300D.
A follow-up... Did a quick google search on your "orb phenomenon". Seems that lots of it are documented on ghost-hunting sites because these are artifacts that pose a problem for ghost-hunters using digital cameras to record sightings :hung: