The Crash 2 trial in 2011 showed a significant but not dramatic reduction in all-cause mortality when tranexamic acid was administered to trauma patients. IIRC, the benefits were not time-dependent up to 2 hours post-injury, which means unless you have really long transports, there doesn't seem to be much reason for EMS to give it.
The drug has been actually been around for quite a while, and is used in certain surgeries with a high potential for blood loss, both IV and oral.
The results of the trial were promising, but for some reason I have a feeling it is a bit of a fad that will be in vogue for a while and then fade away.