There is no way to know on the phone itself. You can run speed tests and see what your upload speeds are to get an idea...
I'm not sure what the reason you want to check is though. The speed difference between Rev. 0 and Rev. A on download is pretty much nill and you're probably not doing intense uploading from your phone.
Also, the towers in your area play a major role. Just because your towers are REv. A. capable and your phone is doesn't mean you'll always get Rev. A speeds. The tower might be saturated or something in your environment could weaken your signal, among other things...
Basically, if your phone shows EV be happy
well until WiMax hits Sprint on a PPC.