Update: Some people have emailed me saying that they beleive this is a phishing site.
It is definitely not.
This promotion can in fact be accessed directly from the home page of paypal.
Registration Linky
You must register and make a purchase between 02/08 and 03/31.
You must have paid $30+ in one transaction.
$15 will be deposited in you paypal account by 05/28.
When i clicked the link, it told me that i need to recieve an email invitation!