I have downloaded Lucene 3.0.0 and
when I used the command
java -jar lucene-core-3.0.0.jar in the directory where Lucene is present
I got this message
java -jar lucene-core-3.0.0.jar
Failed to load Main-Class ...
I've written up a quick howto on getting multicore going: http://charlesleifer.com/blog/solr-ubuntu-revisited/
Following instructions from the two sites below, I've installed Tomcat 6 and Solr 1.4.