Are there any plans in the works for adding instant messaging to the site?
I don't think you are really asking about IM in its true definition, as there is already instant messaging on the site. You go to "who is online" to check if the person you need is online and send an instant message. The recipient gets the message instantly.
You are probably asking for the ability to add buddies, to get notification when they are online and to be able to chat directly in a window. If so, yes, there is a plan to do this and it will be done in the next few months. However, right now there are higher priorities:
1) Bonuses. Expect to see it REALLY soon, within days. It will be big. No longer will your score be limited to "answered correctly times 10."
2) More games. An hourly game, a gold members-only game, etc., etc.
3) Team Divisions
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