Accodring to a SecurityFocus advisory found at http://online.securityfocus.com/archive/1/278984 Acroread 5.05 (as well as some previous versions) have a major temp file explot vulnerability. I believe that it's in users best interest to mask this ebuild until Adobe fixes the issue.
Thanks much for this Jago! A Gentoo Linux Security Announcement has been sent to all the mailing lists. Additionally, the new acroread ebuild is just a wrapper which calls xpdf and warns the user to unmerge acroread :)
Right now attempting to emerge acroread will install xpdf. While XPDF is good for basic things, you might want to try "app-text/gv" if you need a slightly more advanced alternative to AcroRead.
