At Sony's E3 conference today, the company has revealed a new optional subscription based service for users of the PlayStation Network.

PlayStation Plus will be available at the end of June and will cost $49.99 for a 1 year subscription and $17.99 for three months. Sound like Xbox Live Gold Membership? Well, kind of, but subscribing to this service will give you access to early demos, avatars, beta tests, early map packs and DLC, discounts and some exclusive content.

Unless we misheard, we're sure Sony said that you get access to the content as long as you're subscription is running. That sounds like you lose the content if you stop your subscription at any time?!? Sounds a bit mean, we'll have to get clarification on that.

Anyhow, there you go. It was bound to happen, you can't blame them really, but you don't have to subscribe if you don't want to.

Edit - Rob B has some more info to add:

Playstation+
$49.99 for 1yr (3months free for intro offer)
3months $17.99
Exclusive content
Early demos
Beta invitations
Free PSN games/PSN minis/themes
PSN discounts
Auto downloads (to push demos/patches/videos to the user)

First month users get:
2 minis (fieldrunners, age of zombies)
Wipeout HD
Infamous trial
PS1 Rallycross
some avatars/map packs

Next month - As well as more of the stuff above you get Core HD show.