Community Manager Abigale came on the forums yesterday to announce that this week's beta event would be extending a little longer than planned:
"Thank you for your feedback and for your patience as our team keeps working to prepare Rift for future betas and release. We'd like to show our appreciation by extending the beta for another 4 hours! Servers will be open until Friday, 2 p.m. (PST) ."
RIFT's third beta event is featuring the 1-20 zones for both Guardian and Defiant factions. Players testing the game have access to two dungeons and the mass rift invasions that are becoming the keystone of the PvE experience.