I was driving along and all of a suddent the "No Key" signal came on. The key is in my pocket as it always is. Could it just be a weak battery? I remember the thread about the key completely dying and leaving people stranded. I hope this isn't the early signs of the same thing

 

I would say it's probably low battery. Take the key out of your pocket and put it in the intelligent key port (down and left of the steering wheel).

 

Even if the ikey battery were completely dead, you should be able to start the car through the port.

 

My 'intelligent' key acted not so intelligent the other day as well. I walked up to my car to press the unlock button and nothing. I tried the disarm button on the key. Still nothing. I ended up pulling out the key and getting in the good ol' fashioned way and just stuck the key into the slot to start the car and got home.
Took the 'dead' key to the dealership to get it fixed/reprogrammed/exchanged and kept making sure, even up to the point of walking thru the dealerships doors, that the thing was dead. The service guy comes out, I tell him the problem and he says lets go check it out. Walks up to the car and bingo, doors unlock, car starts and the darn 'smart *** key' works perfectly fine!
I had to try it a couple of times myself just to convince myself of what had just happened.
According to my service tech, the keys erratic behavior could have been due to outside frequencies throwing off or completely blocking off the keys signal to the car. First thing he asked was if I parked the car near an area where there are several radio and tv broadcasting stations. I said 'as a matter of fact, i do'. I guess that explanation seemed rational enough for me since the key was now working perfectly fine.
The thing that still baffles me, though, is that I've been parking in the same area for months and that was the first time it ever happened. Not only that, my key didn't work at home(which is no where near ANY broadcast stations). Maybe it needed time to reset itself...?