At one of the recent meetings of the Renegade Writers' Group I attended I betrayed my lack of knowledge of the writing process. One of the attendees read out a story and listening to it I had the distinct impression that the POV jumped around a bit and said so. I was then informed (firmly) that the story had been written in Third Person Omniscient.
It seems that TPO is written from the viewpoint of an all-knowing narrator and not from the POV of one of the characters. I had never really thought about it before so I did some investigating and low-and-behold it seems that it's the preferred aspect for such luminaries as Tolkien, Jane Austen and John Grisham, to name just three. The advice is that it's particularly suited to sweeping fantasy tales and those with multiple characters.
My opinion is that it's also bloody difficult to write effectively. The problem seems to me that written badly it evokes a lack of involvement, everything seems to be at arm's length and it takes a master (or mistress, in Austen's case) to prevent it coming across as flat and emotionless. Of course, it's a personal thing but that's probably why I've never been a great fan of 'The Lord of the Rings', it was just too uninvolving. Grisham pulls me in because his books are so dialogue heavy and the peerless Ms Austen does it by using a device which is anathema to modern editors, lots of letters (too much 'tell' and not enough 'show' for modern sensibilities).
No, I think I'll stick to Third Person Multiple for the time being: at least then I'll always know which character I am at that point of time ... though it's a bugger when you're writing the fourth book of a quartet remembering what each character knew or didn't know. But at least they get to live a little.