South Florida Sun-Sentinel, Fort Lauderdale, FL, 1/5/12:

Story is here.

They're marketing this (either a media misunderstanding or the agency providing misleading information) as a train to the airport, when it's not. One will have to make a transfer at the Miami Intermodal Center with the MIA Mover, the people mover that opened this past Fall between there and the actual airport, the site where somebody can board a plane. The Airport Link (also known as the Orange Line) will end no closer to a functioning airport than the Newark Airport station on NJT/Amtrak, or the Airport station on Boston MBTA's Bule Line. So Miami should not consider themselves to be in the same class as Cleveland or Chicago in having a heavy rail station at an airport.
Just how many national train services are there besides Amtrak?

Miami, FL Herald, 1/28/12:

This story is here.

Miami, FL Herald, 2/19/12:

And this makes perfect sense. I think this was the intent all along, because as I understand it, signage already was changed to allow for concurrent Green Line (existing) and Orange Line (future) services between Dadeland and Earlington Heights. Of course if the other proposed segment of Orange Line up to Sun Life Stadium and Calder Race Course is ever built, then a transfer will have to become necessary from most Green Line points. And now that I'm done, you can read the story here.

Unofficially, (and I say that because the only definitive date I've seen has been on Wikipedia) the MDT Orange Line is set to open on Monday, April 30, 2012. If this is in fact true, it will result in a double thrill week with L.A.'s Expo Line also opening around then. Hopefully a more official announcement in the local media will be made soon.

Nothing in the local Miami media about an opening this week. MDT's website still shows the MetroRail map with only the Green Line. So unless this is being done in secret, assume that the Orange Line opening isn't going to take place by the end of April.

MDT website now says the AirportLink (aka Orange Line) will open Summer 2012. That gives them a whole 3-month window. Maybe they will make it during that time?

OK a definitive date was announced today. It'll be July 28, 2012. The new Orange Line spur and will open on that Saturday. The transit portion of the Miami Intermodal Center station will open 6 days earlier on Sunday the 22nd. From South Florida Business Journal, 6/14/12:
Story is here.

And by coincidence this ends up being the same weekend that DART in Dallas will be opening its next light rail segment, also an Orange Line!

Miami, FL Herald, 6/28/12:

Story here.

Progressive Railroading, 7/13/12:

Details