From victor kruger via the CCCKC Mailing List

If anyone decided to purchase a Palm Pre (besides me) I’m happy to say
people have already found several interesting items in order to hack
the Pre.

One of the more funny findings is how to enable the dev mode on the
phone. you first go to the app menu/launcher and type
“upupdowndownleftrightleftrightbastart” .

From Engadget:

We couldn't believe it either, but as it turns out, from the launcher screen of your Pre, simply type in the phrase “upupdowndownleftrightleftrightbastart” — which if you parse with spacing might be more easily recognizable as the infamous Contra / Konami code look it up — and up comes a hidden app called “Developer Mode Enabler.” Looks like it was discovered via the leaked ROM from earlier this evening. It's apparently used to connect a Pre to a machine running Palm's Mojo SDK for webOS, and we have confirmed its legitimacy. In fact, if you want proof and you don't have a Pre of your own, head on after the break for a video we put together, just for you.

Another more interesting find is the recovery tool in case you screwed
up an update for the phone and it is also used for switching ROMs on
the phone which includes the normal consumer ROM and the Developer ROM
for the upcoming SDK. This recovery tool is in the form of a jar file
which even includes the complete linux file structure for the phone.

People have already modifying their pres to do things like increase
length of the vibration when you receive a text message to gutting out
a non essential app on the phone (I.E. Sprint Nascar App) and putting
in a hello world app inside.

http://forums.precentral.net/web-os-development/184378-ok-rom-comes.html

fun times ahead….fun times…