enter/leave session triggers

Hi,

Have there been any discussion on the list on triggers fires when new
session (libpg session to server?) is opened/closed? Somehow I cannot
google anything with the keywords I use.

And the question is: has postgresql any plans to have:
1. triggers that fire BEFORE/AFTER user opens a session with server?
2. triggers that fire BEFORE/AFTER user ENTERS/LEAVES a role?

the simplist use is to have session timestamps logged in application
speciffic tables; but I personaly find myself always having a "users"
table, full of attributs which quite often are there to setup user
profiles for the duration of sessions and to be persistent across
sessions.

-R