You could alternatively just go with patching the JENKINS_HOME so Jenkins considers it not an update:
$ echo -n 2.0 > $JENKINS_HOME/upgraded
$ echo -n 2.0 > $JENKINS_HOME/.last_exec_version
The files are being renamed in https://github.com/jenkinsci/jenkins/pull/2215, but for beta 2, the above appears to work.
But please note that this is considered internal storage so may not work this way forever. I think we'll pretty quickly introduce a supported alternative way though.
Based on comments by Keith Zantow earlier in the 2.0 development cycle, I was under the impression that setting the system property jenkins.install.runSetupWizard=false would suffice.
Apparently this is not true.
For me, and my co-maintainer of the puppet-jenkins module Joshua Hoblitt, I believe the lack of a consistent and supported way to disable the "Getting Started" wizard is a blocker for 2.0. We cannot build reliable automation around provisioning Jenkins 2.0 (Puppet, Chef, etc) without it.