It's actually been there for over a year.
We used it October 2012, again in Spring 2013 and October/November 2013.
As pug dog mentioned, it was roped off and the rope has a Handicapped symbol on it. It is available for guests with visible disabilities, but not required to use it.
It is becoming known; 2 times we were at Columbia Harbour House, it was full (even though a CM at the counter suggested we go there).
It is nice to have the extra space and nice if there are tables there, but you can't completely count on it.
If it's full, CMs will try to help you find a spot.
Its been there a lot longer than people think.
They actually started it in August 2011, I know as that's when we were there.
They said they had just started a new system in place for disabled users to order and where to sit. We were directed to an end till, which was then opened for us to order and then we were escorted to the area to sit in.
Hahahaha this may be inappropriate but are we taking bets on how long it takes someone to be offended by this, have a CM imply a handicap person MUST use this area or for a guest to misunderstand a CM and think they're saying they have to use it?
well Ive got to say I was offended right away.

I think as the system had only just been set up, they hadn't fully appreciated it should be an option. So they were very forceful in making us sit there.
It really didn't feel right to us, we did return but It was quiet so I found a table and sat there. The amount of cast members that kept coming up and telling us that we had to sit in the wheelchair area was frustrating.
I did post about it on my return but no one seemed interested.
I know there is a need, to have some free tables for people who can not use stairs. I have worked in fast food restaurants in the past, where there has only been a handful of tables downstairs. I have found, its much easier for the cleaning staff around the restaurant to mention to customers that we also have seating upstairs.
It felt like a few times on our last trip, that they were changing their ways toward the disabled. To me it felt like going back to the old days when the disabled were segregated.
I remember when we were at the Haunted Mansion and due to having a wheelchair, we had to go a different way. The cast member shouted- out the way handicapped family coming through. Of course that made every turn around and look at us.
This is only a couple of instances in otherwise a great couple of weeks.
We're going next August, it will be interesting to see how things are now.