They've been easily available for several years.

The lever is one that has to be flipped by hand to engage or disengage the pedals. They have a cleat that locks in place when the lever is flipped. It still really needs a toe strap and clips for complete security (as in on the track). I wouldn't consider it for road use because you have to reach under your foot to flip the lever and it isn't the easiest/biggest lever to grab in a hurry. The pedals are the same as MKS Nuevo's with the lever hardware added (it does require a small change in the front and back plates to accommodate the locking hardware, but think of it as a Nuevo with the extra hardware. It is not NJS, by the way, if that matters to you.

Since the options for a good secure track pedal are pretty limited these days, there are new solutions starting to emerge. Riders have been stuck with Dura Ace PD-7400 pedals (clips and straps, with cleats) or with PD-7701 pedals (clipless SPD-R) as decent track power-event-oriented pedals. The 7400's have gotten ferociously expensive and some parts (like toe clips, especially in big sizes) are virtually unobtainable. The 7701's are superb but also getting quite expensive, and they require shoes with SPD-R drillings -- since almost all new shoes are coming only with 3-hole Look drillings, that gets to be a problem. The Exa's are an attempt at a new solution. Personally, I'd just ride a Nuevo with the new MKS cleats that are designed to fit into them -- it's a very nice, classic system that works extremely well. The cleats are available and currently fit the RX-1 pedals; the Nuevos with the modified plate spacing are due out very soon. If you aren't actually racing but want clips and straps (and if you also want NJS), this is the way to go. If you're a serious trackie, you already know about 7400's or 7701's and have found a couple to ride.