A reasonable solution to this is to not use real OpenStreetMap data and instead use fake data stylized in whatever way you think gets the message across. As to using real OSM data, likely anything useful as a logo will be so small that from an ODbL pov it will be a non-substantial extract [non-substantial extract](http://wiki.openstreetmap.org/wiki/Open_Data_License/Substantial_-_Guideline) and not be subject to the licence. However as I've said before the help site is the wrong place for legal consulting.

A reasonable solution to this is to not use real OpenStreetMap data and instead use fake data stylized in whatever way you think gets the message across. As to using real OSM data, likely anything useful as a logo will be so small that from an ODbL pov it will be a non-substantial extract and not be subject to the licence. However as I've said before the help site is the wrong place for legal consulting.