I don't care if it was just to turn the phone off—the fact the Palm Pre uses the Konami Code for anything is amazing. In this case, you type in "upupdowndownleftrightleftrightbastart" in your phone to access dev mode.
According to Engadget, dev mode is apparently what allows you to connect to the upcoming Mojo SDK, and test out your latest creations on the phone.
And in slightly related news, a copy of the WebOS root image also leaked, giving code monkeys a look at the inner workings of Palm's mobile platform, PreCentral reports. It doesn't necessarily mean anything quite yet, but it opens up the possibility of some Pre and WebOS hacks in the future. Fun! [PreCentral and Engadget]