FSF Europe has come out with a good report on what to do about open source license violations. They cover:
- how to report a license violation,
- how to respond to a license violation notice,
- and how to avoid license violations.
Their advice for reporting a violation is very specific and detailed - worth reading. They cover things from what information you want to include in the report to where to send it.
The information on how to avoid license violations is not as detailed - it basically says to read the license and get help from experts. If you are interested in avoiding licenses, you'd be better off reading information on open source compliance programs.