nm_pppd_plugin.so links against the installed version of libnm-util, rather than the newly built version. This means it will fail to resolve after upgrading from 0.7.0 to 0.7.1 (or downgrading). Patch attached, and will open upstream bug.
Created attachment 189324 [details, diff] Link against newly built version of libnm-util.so
*networkmanager-0.7.1-r1 (25 Apr 2009) 25 Apr 2009; Robert Buchholz <rbu@gentoo.org> files/networkmanager-0.7.0-gentoo-dhclient.patch, +files/networkmanager-0.7.1-bad-link.patch, -networkmanager-0.7.1.ebuild, +networkmanager-0.7.1-r1.ebuild: Fix bug #267349 by Daniel Gryniewicz, NetworkManager-0.7 links against installed version of nm-util, specify udev directory for bug #267168.