You don't need an invite anyway, when I go on to my control panel on www.ideas.live.com there's a link for that which says try it, unlike some of the other products like the live messenger!!!
i saw that on the services pageInformation for current MSN subscribers:
All existing MSN Hotmail Extra Storage subscribers will be automatically upgraded to MSN Hotmail Plus at no additional cost when it becomes available this summer. No action is required on your part.
Same here. I have no choice but to wait invitation.i saw that on the services page