First and foremost, OWATray is a freeware tool. You cannot bundle it with your own commercial application and you cannot sell it in any way, shape or form.
As an individual, you're allowed to use it anywhere you like - be it at home or at work (assuming they don't mind of course!).
I'm not against it being rolled out in a corporate environment, just make sure the users know they are supposed to contact you with any support type issues and not me - I'm not an extension of your helpdesk!