Back when UDK was first annouced both myself and INtense! agreed that UDK would not need it's own profile because is it in a nutshell a variant of the Unreal 3 engine. Up till now we have had developers list their UDK creations as Indie using the Unreal 3 engine, it felt like the right choice.
However since the release of our new sister site IndieDB we can see that this is going to be a problem for many as commercial games that use UDK could not be correctly listed. To fix this problem we have just created a new engine profile for UDK which will have all the content from the UT3 engine profile moved over. If you had your project listed with the old arrangement don't worry I have already fixed your profile to correct these changes (though if I made a mistake shoot me a PM, after all I'm human I make them once a blue moon).
The engine can be found in the engine drop down now if you have listed your project incorrectly please make the changes when you can.