http://bumped.org/psublog/phantasy-star-online-2-closed-beta-test-starts-april-19-2012/
A wave of emails have been already sent out; more waves are expected to come. Check the email that you used to register for the beta, if you did.
There is still time to register for the betas (until the 16th): Do it now if you want to get in.
If you already have an SEGA ID on the Japanese SEGA site:
http://www.pso-world.com/forums/showpost.php?p=2727074&postcount=162
If you don't not have a SEGA ID:
http://www.pso-world.com/forums/showpost.php?p=2727083&postcount=166
Note that a US ID won't help.