It's still open, but it's not really walkable from the terminal, you can only get to it from the highway (Texas highway 71). It's located directly to the east of runway 17L.
If you rented a car, you would go towards the highway on the road from the terminal, but then turn right on Hwy 71 rather than left towards Austin. The very first right is a little two lane road, it leads back to the observation area. Great place to watch planes, although Austin doesn't exactly have an exciting assortment. Lots of 737's and MD
-80s, with an occasional DC-9 and A32x. FedEX flies in the DC-10, but they use the longer 17R/35L. There are also some cargo 762's.
Firings, if well done, are good for employee morale.