From OSGeo Wiki
This page shows a selection of all official OSGeo Foundation logos in PNG format and several resolutions. For full scalability use the OSGeo Logo SVG version available in SVN together with more versions and formats: http://trac.osgeo.org/osgeo/browser/marketing/logo
Please make sure to read the OSGeo Trademark Guidelines!
Please use these logos sensibly to keep our brand clean. If you have trouble finding the right size or format please contact us.
The general OSGeo tag line is "Your Open Source Compass". There are three additional official tag lines for the sponsors reading * "Sustaining", "Supporting" and "Associate". Two special versions have been designed for OSGeo projects reading "Project" for graduated projects and "Incubation" for projects that are still in incubation. These versions may only be used by Open Source software projects which have applied for Incubation or graduated and comply to the OSGeo quality criteria - the OSGeo way of doing Open Source Geospatial.
The corporate color is green. The logo uses 9fcf67 for light green and 47aa42 for the darker green. The blue text uses 0055a5. You can also use create a logo with a bright green 00ff00 version if it looks better on a slide show or stitched on black.
'OSGeo' is written in Trebuchet MS, more info: | wikpedia
'Your Open Source Compass' is written in TheSans Plain Itali, more info: | lucasfonts.com