Looks like it's up now. I was able to create an account and sign in.
Caveat: The "activate your account" email that they send you has an incorrect link to the activation page. To correct the URL, just insert a '/' character as follows:
WRONG:
http://www.prslabs.com/auth_develope...account.php?m=....
RIGHT:
http://www.prslabs.com/auth_develope...account.php?m=....