foo_wlm
My first attempt at a plugin .
Let's hope I compiled it correctly such that it works.

foobar2000 1.0 and above: Download v1.1.8a (25th Feb 2011)
foobar2000 0.95 (No longer updated): Download Removed (21st September 2009)
You may use the following titleformatting variables in your PSM:
- %streamname%
- %isstream% - Usage Example: $if(%isstream%, 'is stream', 'not stream')
For people who do not have WMP and want to use this plugin: Read this post for a workaround (Thanks Niels!)
Important Note:
As WLM has apparently forced a "%title% - %artist%" format on your contact list from Windows Live Messenger 2009 (WLM 14.x) onwards, changes have been made from V 1.1.0 to work around this. However, this doesn't follow WMP's format/standard. Additionally, on this plugin, you are recommended to have a " - " (that is a space dash space) in your custom media format.
If that pattern isn't used, there will be an additional dash behind your message. Do note that this only happens on your contact list and not in the convos.
With Dash Pattern in WLM 2009 (WLM 14.x): 
Without Dash Pattern in WLM 2009 (WLM 14.x): 
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For those who do not want a PSM to be displayed when you pause your track, use the following TF (editable in preferences -> WLM):
$if(%ispaused%,,%title% '-' %artist%)