Using a 276-640 instead of a tsop 1236
You won't find a datasheet for a 276-640 because it's not a manufacturer's part number, it's a Radio Shack catalog number. I find components without datasheet pretty useless.  

I wouldn't call Radio Shack avant garde when it comes to offering newer parts. I think Vishay's parts are well up-to-date. For instance, all recent parts work with voltages down to 2.5V.
Even so, the capacitor is always recommended, no matter how new the receiver is. If you don't place it the receiver will cause minor spikes on Vcc.  

Another note on the 276-640: keep in mind it has a carrier frequency of 38kHz, whereas for the TSOP1236 this is 36kHz. Things you'll find in the datasheet... (at least for the TSOP1236, for the 276-640 you can find this information on Radio Shack's webpage, but there's no other info than that...)