Today (2008-01-12) I loaded Pidgin and discovered that I was no longer able to connect to MSN. It appears either Microsoft is blocking the connection or a new version has been release. What the cause of the matter is I have not been able to verify with certainty at this time.
UPDATE: Pidgin v2.5.4 has been released that temporarily fixes the problem.
“Unable to Retrieve MSN Address Book using Pidgin”. See screen shot of the error message below.