No, no, it's a photodiode (my best guess). Both emitter and receiver look exactly like LEDs. In fact, poking around the net a bit, they look exactly like these on the right:
The resistance of the receiver goes from crazy high (many M, hard to measure as it jumps around a lot) to about 50k when put head on and touching the emitter. I initially powered the emitter with around 10 mA, then changed it to 100mA daring it die. So far it hasn't, although it's hard to tell with IR (I look at it through a phone camera but it's not an exact science :P). It doesn't get particularly hot (though I only let it run a few seconds at a time to take measurements) and occasionally swap with a new one (I have three) to see if I get any differences. So far it handles the crazy high current quite well, although I don't think it makes such a huge difference to the overall performance as a sensor (if I understand correctly, LED efficiency drops a lot as current goes up so there's not much point pushing them after a point. I have no idea where that point is for IR LEDs but I 'll probably find out).