"Glassbeed" has an interesting post about Kids and Digital Identities today.
I originally had several online IDs in order to keep professional, personal, and political commentary separate. I was concerned that prejudice about my personal views might color people's perceptions of my professional capabilities.
I quickly realized that it was far too much work to keep them totally separate. If someone takes a dim view of my professional contributions because they don't like the way I vote or worship, that's their problem.