1. A method in a computer system for managing collaborations, the method comprising: receiving, by the computer system, a request for collaboration on a topic; identifying, by the computer system for a collaboration, a plurality of experts that have expertise in the topic, wherein at least two of the plurality of experts have a different one of a plurality of different threshold levels of a likelihood of participation in the collaboration, wherein the likelihood of participation in the collaboration is the percentage based estimation that the expert will participate in the collaboration based on a relative location of the expert to a collaboration site and whether the expert belongs to an organization hosting the collaboration, and wherein the plurality of experts are identified using a number of collections of information; setting the plurality of different threshold levels according to a level of expertise of the plurality of experts; and identifying, by the computer system, particular experts of the plurality of experts that have a respective particular likelihood of participation that exceeds one of the plurality of different threshold levels.
5. The method of claim 1 , wherein the number of collections of information comprises prior communications by a user sending the request.