The double referral bonuses have been available for college students (anyone with a @.edu or equivalent email address) for quite a while. Glad to see it's available for everyone now!
The part that gets me there is that paid users got doubled to 1GB instead of the 500MB and EDU users got no benefit from the bump. (It's free, so I'm not complaining very loudly)
And it is also now that you can get in retrospect the referral bonuses.