Maybe everyone else knew about this, but I just found out voice recognition is build in to Windows RT and is on the 2520. Under Apps, look for Windows Speech Recognition, set it up, and have fun. Make sure you go through the online tutorial video.
Windows Phone is supposed to be getting a new Siri-like voice assistant with the update to 8.1, codenamed Cortana. Hopefully that will make its way to RT as well.