A themer on Android.net posted some Gingerbread keyboard themes I thought I'd share with the PE community since 4.2 runs the GB keyboard. I installed red on black with no problem at all (obviously, make a back up just in case; of all the threads I've read and problems I run into, each phone is different).

Available colors (1/31/11) : Red gradient, red on black, blue, yellow, and green (looking at the screen shots it looks like it could be a very close match to the 4.2 green). Page 3 of that thread has a few other keyboard themes as well.

{THEMED APP} Gingerbread Keyboard - Various Colors