1. A method for handling instant messaging sessions in an instant messaging server, comprising: providing global annotators for annotating instant messaging communications, wherein instant messaging users are being able to select for a private enhancement stack at least one of the following: annotators and look-up services; providing instant messaging users with a capability to obtain contextual information by activating enhancement functions provided by said private enhancement stack; establishing an instant messaging session between a set of instant messaging users; and supporting sharing said contextual information among said set of instant messaging users as part of the instant messaging session.