What is SETI@homeBETA?
SETI@HomeBETA is a test project for SETI@Home. I think they are testing new SETI@Home applications before putting them into use for SETI@Home. According to The Unofficial Boinc Wiki page, whatever the hell that is, "The SETI@Home Beta Test Project is where the next generation of the Science Application is tested before it is released for use by the SETI@Home Project. This Project is a 'companion' which will only be active on those occasions when a new version of the the Science Application is under development."
So, there you have it.