As you might have heard me talk about on the podcast I pre-ordered a Surface Pro 2 and when it arrived was disappointed that it came with the power supply connector from the first generation Surface Pro. I’ve since contacted the Surface support team and they have ordered a replacement, although they still couldn’t guarantee that it would be the updated version. While on the telephone with them they noticed the device wasn’t registered and gave me the URL so that I could register my Surface 2.
Here, after signing in, you can register your Sruface devices and after that I discovered that you can order replacement accessories directly from that page! Now apparently it was stock issues that resulted in Gen1 power supplies being packed with the devices so you might still get the old model. Worth a try if you ordered a Surface Pro 2 but also useful if any of the included accessories break or are lost (like the stylus for example).
If you can’t locate your serial number then this page should help:
Thanks to @scottisafool for that last link.