LinkedIn is good in case if the person is a member on it.
google can of help in case the person is into blogging, social networking and all so that you can dig out info.
one of the easiest way is if you have access to job portals as a consultant /company you can search his cv - you must have a full name of the person you are seeking info about.
make a dummy call requesting for his updated CV if you have his number.
Or
request for an updated cv though email if you have his email ID.
regards
MB