Doing a daily upgrade in raring, I noticed that update-manager had stalled. Looking at the process list, I found the following:
root 25694 0.6 1.0 294444 41088 ? SNl 08:02 0:20 /usr/bin/python3.3 /usr/sbin/aptd
root 28523 0.0 1.0 294448 39180 pts/22 SNs+ 08:17 0:00 \_ /usr/bin/python3.3 /usr/sbin/aptd
root 31694 0.0 2.4 130352 92924 pts/23 SNs+ 08:18 0:01 \_ /usr/bin/dpkg --status-fd 78 --unpack --auto-deconfigure /mirror/ubuntu/pool/main/p/perl/perl-modules_5.14.2-17_all.deb /var/cache/apt/archives/libc6_2.17-0ubuntu1_i386.deb /mirror/ubuntu/pool/main/e/eglibc/libc6_2.17-0ubuntu1_amd64.deb
root 31729 0.0 0.0 61040 524 pts/23 SN+ 08:18 0:00 \_ /usr/bin/perl -w /usr/share/debconf/frontend /var/lib/dpkg/tmp.ci/preinst upgrade 2.16-0ubuntu8
root 31739 0.0 0.0 4412 264 pts/23 SN+ 08:18 0:00 \_ /bin/sh /var/lib/dpkg/tmp.ci/preinst upgrade 2.16-0ubuntu8
root 32033 0.0 0.0 17516 264 pts/23 SN+ 08:18 0:00 \_ whiptail --backtitle Package configuration --title Configuring libc6 --output-fd 11 --nocancel --inputbox -- Running services and programs that are using NSS need to be restarted, otherwise they might not be able to do lookup or authentication any more (for services such as ssh, this can affect your ability to login). Please review the following space-separated list of init.d scripts for services to be restarted now, and correct it if needed. Note: restarting sshd/telnetd should not affect any existing connections. Services to restart for GNU libc library upgrade: 17 77 saslauthd postfix cups cron courier-authdaemon atd apache2
The restart prompt for libc6 2.16->2.17 is being displayed on the embedded terminal which is hidden by default, instead of being displayed with the gnome frontend like it should be. This was working correctly for me in quantal, although there have been various reports floating around for a while of the wrong frontend getting used.
ProblemType: Bug
DistroRelease: Ubuntu 13.04
Package: update-manager 1:0.178
ProcVersionSignature: Ubuntu 3.5.0-22.34-generic 3.5.7.2
Uname: Linux 3.5.0-22-generic x86_64
ApportVersion: 2.8-0ubuntu2
Aptdaemon:
Architecture: amd64
Date: Wed Jan 30 08:51:50 2013
GsettingsChanges:
b'com.ubuntu.update-manager' b'first-run' b'false'
b'com.ubuntu.update-manager' b'launch-time' b'1359562024'
b'com.ubuntu.update-manager' b'show-details' b'true'
b'com.ubuntu.update-manager' b'window-height' b'778'
b'com.ubuntu.update-manager' b'window-width' b'924'
InstallationDate: Installed on 2010-09-24 (859 days ago)
InstallationMedia: Ubuntu 10.04.1 LTS "Lucid Lynx" - Release amd64 (20100816.1)
MarkForUpload: True
PackageArchitecture: all
SourcePackage: update-manager
UpgradeStatus: Upgraded to raring on 2013-01-25 (5 days ago)
Confirmed here