It may or may not be the same interface as the Parallax.
) they say:
"It’s similar to RDM630 125kHz RFID reader module , nearly the same pins and the same output protocol, user just need to read the UART serial port that you can get the card / tag ID."
In this article: http://iteadstudio.com/produce/play-rdm630-with-arduino/
they give some example code for Arduino. Looks like they just read 11 bytes and display bytes 4 through 11 (8 ascii characters representing hexadecimal digits) on an LCD. The hexadecimal, when converted to decimal gave them the decimal number shown on the tag. There are probably framing characters like on the Parallax so it would be good to check for those. You could also check the checksum to be sure the read was clean.
Too bad that the $19.90 "Sniffer Nano v2.0" (http://iteadstudio.com/store/index.php?main_page=product_info&cPath=16&products_id=220
) doesn't support the 134.2 kHz tags. In this article (http://iteadstudio.com/produce/rdm630-new-version-and-sniffer-nano-v2-0/
) they say: "Not just 125Khz, We found that the 134.2Khz RFID protocol is very similar to 125KHz, so just update the firmware , you can get a 134.2Khz reader like RDM660!" I didn't find the firmware sources, let alone the mods for 134.2 kHz.
Edit: Found the firmware sources: http://iteadstudio.com/application-note/sniffer-nano-source-code-v1-0/
Changing the frequency may be as easy as modifying some timer parameters in InitialTimer().