Solr can't find lib files
I was having the same issue.

I ended up copying the contrib folder into: /usr/local/tomcat
So I had: /usr/local/tomcat/contrib/
and: /usr/local/tomcat/solr/drupal/

That error about contrib/extract/lib went away, but now I'm getting: 
"Failed to load file /usr/local/tomcat/solr/drupal/solrconfig.xml"

As seen on the logging screen: http://screencast.com/t/MqtSNpqUljI

UPDATE: I went to the admin section on Solr and tried to add the core called drupal. So it tried to process the solrconfig.xml and found an error: http://screencast.com/t/EEmU4P9M 
I had the useCompoundFile twice. I fixed it and added the core. After that, it was working fine.
I hope this helps out someone. I installed solr on centos by following the lullabot guide: http://www.lullabot.com/blog/article/installing-solr-use-drupal