Thanks for the answer Unfortunately this is NOT it. The blue bar is the same in Messaging, Email and Contacts. I already had a look and changed everything I found in framework-res.apk, moto-res.apk and SystemUI.apk ... I'm kinda desperate!
Don't forget to check blur-res. I would guess its either there or fw-res, based on the aps that are using it.
blur res/drawable check actionbar_bg.9 or maybe badge_bg_new.9 ?
blur res/drawable hdpi badge_bg.9?
sorry, not able to dig much right now, but based on what mine looks like right now, those may be it
FINALLY. The images were placed in the moto-res.apk. I already edited them but forgot to replace the apk *facepalm* ... Finally, I now have a black and blue UI
Have a look: Themed Framework for more ICS style - xda-developers