Last night cyanogen aka Steve Kondik announced that the T-Mobile Samsung Galaxy S4 will start getting CyanogenMod nightlies starting last night.
As of now the build is not up on http://get.cm/?type=nightly but we are hoping it should be up tonight. Here is what Steve had to say on his Google+ :-
Galaxy S4 CM-10.1 Nightlies
I just finished the initial bringup of the T-Mobile Galaxy S4 (SGH-M919). We’ll port to other variants when we get the devices (including the I9505). The first nightlies will go off tonight. There are a few rough edges still, but will be ironed out in short order and you should be able to use it as your daily driver without serious issues.
The touchscreen on this device should support Android’s hover events. I’m looking forward to see what the community can come up with using this new feature!
Compile/fork/install, contribute back, and enjoy
So if you have not yet installed a custom recovery on your T-Mobile Samsung S4 then we suggest you do that soon, let the flashing begin!