Sony's PlayStation Access is offering Facebook users free 30 day trials of PlayStation Plus.
In order to receive a voucher code to activate the free trial you'll need to enter your details into a Facebook competition form. There's also a competition to win a year's free access.
In order to activate the trail you'll need to attach a debit/credit card to your account, enabling Sony to automatically renew your membership for 90 days once the 30 day period is over. To avoid any unwanted charges be sure to cancel your PS Plus membership, which can be done at any time during the trial.
Source: PlayStation Access. Promotion is not run in association with VideoGamer.com