Asus is still releasing Transformer tablets on a regular basis, but most of them are mid-range. The premium device in the Transformer family is still the TF701T, and it's getting an update to Android 4.4.2 right now. The OTA is happening, but it looks like a slow staged rollout.
Asus has kept up with the TF701T fairly well. It's running a few months behind the curve (Android 4.3 was in December), but at least it's still getting OTAs. We have at least one confirmed report of an OTA, but our unit hasn't been updated yet.
The update files have been posted on the Asus website if you don't want to wait. There are multiple SKUs, so you have to be sure to download the right one (each is about 1GB). Past devices have required you to put that update ZIP on an SD card and load it into the tablet to trigger the normal update process. That should still work, but the lack of documentation makes this a "proceed at your own risk" scenario. It might reset the tablet, even though past devices didn't do that.
[Asus – Thanks, Andrew]