The OSGi Execution Environment and/or the minimum JDK should be mentioned in the FAQ, release notes, and readme.

Also, MANIFEST.MF should be marked appropriately (Bundle-RequiredExecutionEnvironment directive).

http://wiki.eclipse.org/index.php/Execution_Environments#Standard_Execution_Environments
http://www.eclipse.org/eclipse/development/eclipse_project_plan_3_3.html#Appendix1