For anyone who has ever asked if MXD's can be created or altered through Python, there's a good chance the answer is "yes" if you use comtypes.
It is a new feature of arcpy to get access to mxds and its contents with ArcGIS 10, isn't it?
Have a look at the new "mapping" module: http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//00s300000032000000.htm
Read this thread from Frank Perks (another genius) for a different example: http://forums.esri.com/Thread.asp?c=93&f=993&t=289397#927436
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It's very, very slow compared to ArcObjects in VBA, but it works. (Hopefully the arcpy module when alleviate this need at some point.)