As we head towards a public release, here is a Web Map Service (WMS) for Open Street Map tiles to test out our upcoming spore technology. Don't worry about what it is yet, just go ahead and use the service as it's a free.
OSM WMS 1.1.1 Capabilities Link
The server implements EPSG:4326, so all requests are made as such. Only JPG support is available as well, since OSM is not transparent and this conserves bandwidth. It has been tested with Google Earth, GAIA, uDig and QuantumGIS. As of writing this, QGIS doesn't support jpg servers, so it will not work. Should work with most other WMS servers. Enjoy, and feel free to report bugs or feature requests in our forum.