Can you use the Apple Watch with an iPod touch?

On every page about the Apple Watch, it's stated at the bottom of the page that Apple Watch :

Requires iPhone 5 or later.

This means no iPod touch.

From Apple's website: "Apple Watch works with iPhone 5 or later running the latest version of iOS, which introduces the Apple Watch app. So make sure everything is up to date"

Note: While it does say "Requires iPhone 5 or later." in the footnotes at the very bottom of the http://www.apple.com/watch/technology/ mentioned by Matthieu Riegler, nonetheless it's important to note that both the iPhone 5 and later must have at least iOS 8.2 or later. So an iPhone 5 still running iOS 7.x will not work with the Apple Watch.

No, you cannot use Apple Watch with an iPod touch. The Apple Watch app is also not available on that device.