According to John, the Woopra King, beta registrations will be closing once the total number of sites hits 50,000. Currently roughly ~ 45,000 websites are being monitored and recorded, which is a huge enough sample to remove any outlasting bugs that may reside in either the application or the structure of the servers itself. So if you still want in, sign up now at Woopra! Otherwise you will have to wait for the offical release.