Hi Suka, The openoffice-2.4.0 ebuild causes and eerror if shadow is built without "pam" in USE. However, this is only relevant if the "pam" USE flag is enabled for openoffice. I think that the built_with_use check for pam/shadow should be enclosed in an "if use pam...fi" clause.
Ooops, what a stupid oversight on my part. Anyway, should be fixed now. Thanks for reporting, Seemant!