Legal/State Of The License/Making Maps
From a State of the License perspective, the License Working Group thinks this is "done". If you disagree or have other thoughts, feel free to add them here.
Making maps from just OpenStreetMap data
Thanks to the ODbL, this is a no-brainer. Make your map. Put it where you like. Use whatever license you like for the map or what contains it. Attribute the data source, OpenStreetMap, appropriately according to ODbL and the media that you are using. How should I attribute you? will help you ... we have little bit more work to cover every media.
Making maps from OpenStreetMap + other data
If you want to mix other data into the map, a little more care is needed, so we have created two community guidelines to help you.
If you run a commercial website providing a map of the whole world, you probably need to use different sources for different places. If you want to use OpenStreetMap for a country, we call those "Regional Cuts" and our Regional Cuts guideline will help you.
More likely, you want to add different layers of incompatibly-license data on top of an OpenStreetMap base map. Our Horizontal Layers will guide you through translating the concepts of your layers into the ODbL concepts of Collective and Derivative databases. In most cases, your data will be a clearly separate and distinct layer so you should not have any problem.
If you do have problems, then it is most likely because you are trying to add data that is clearly modifying or enhancing OpenStreetMap. So your easiest solution is to share it and that is what we want. Upload your enhancements to OpenStreetMap and then make your map.