Here is a misc. list of documents that may prove useful.

Client

	MSNP Protocol
	Introduction • Terms • Clients
	Reference
	Error List • Commands • Relying Party Suite • Spotlife
	Services
	XMPP • HTTP Gateway • Tabs • Activities
	Documentation
	Development Tools • MSNP Grid
	Polygamy • URLs used by MSN
	Documents
	Protocol Versions
	Version 21
	Version 18
	Version 16
	Version 15
	Version 14
	Version 13
	Version 12
	Version 11
	Version 9
	Version 8
	Version 2
	MSNC
	Introduction • P2P • Object Descriptor • Display Pictures • File Transfer
	Scenarios
	Microsoft Messenger for Mac
	MSNP on WebTV (MSNTV)

Microsoft Messenger:mac v5.1 - Deployment Guide: Messenger51_NetAdminGuide_2.pdf
Microsoft Messenger for Mac 8 Beta Build 08.00.00.100305 - Release Notes: Messenger8Beta_ReleaseNotes_1.pdf
MSN Messenger on PocketPC - Help: 2003_MSN_20Messenger_PPC_1.pdf

Activities

Live Connect Preliminary - Documentation (November 2012): LiveSDK.chm
A Guide to MSN Communication Services: MSN Spaces, MSN Messenger, MSN Hotmail - Reviewers Guide (December 2004): MSNWave10RG_1.doc
A Guide to MSN Integrated Communication Services: MSN Spaces, MSN Messenger, MSN Hotmail (April 2005): MSNWave10RG_5.doc

If you have pcap files from Messenger, it would be interesting to share them as they will be useful in order to understand the protocol.

On pcapr.net (now defunct), a search for "msnms" gave these files: