In the doc for the RemoteIpValve (http://tomcat.apache.org/tomcat-6.0-doc/config/valve.html), the remoteIPHeader attribute is mentionned, but actually it should be remoteIpHeader (notice the lowercase "p") since the setter method is setRemoteIpHeader(..).
Thanks for the report. I've cleaned the code and the docs up for 7.0.x and that will be in 7.0.1 onwards. I have also proposed a patch to clean up 6.0.x.
Fixed in 6.0 in r958195 and will be in 6.0.28 onwards.