Lenovo S12 Intel Atom laptop, new Arch Linux (systemd)/Gnome 3.6 install.  Broadcom NetLink BCM5096M Controller, b43,b43-fwcutter and b43-firmware installed and verified. networkmanager 0.9.6.4-1

At boot… 
# systemd-analyze blame
 85761ms NetworkManager.service
  4436ms sshdgenkeys.service
  4426ms polkit.service
  3977ms accounts-daemon.service

Connection is slow, iwconfig reports 18 Mb/s (compared with 40 or more on MSWinXP)

At startup, system connects normally.
If ignored for a bit, the screen goes dark.  When re-illuminated after a rather long time, NetworkManager has dropped connection and will not (re)connect to WiFi, or connect to a 2ndary WiFi channel.
A pop-up opens asking for the password, which it has, the text-box filled with a bunch of "•"s.
It has the correct passwords, and always reconnects when system (rebooted) or networkmanager restarted .  NetworkManager worked normally with a prior distro (Ubuntu12.04).
The lap top is set to never suspend, and set to poweroff if low battery.  If the screen off/on is not too long, the connection will be kept.

netcfg has been removed from the system, and net-auto-wireless, net-auto-wired are inactive.

power management is off.

Attempts to test with a TP-LINK USB Wi-Fi USB dongle failed because could not authenticate wireless connection with AP, same failure as with laptop wireless after connection dropped.

I booted the S12 at 4:30 p.m. and the next morning it had lost the wireless connection over night.  I ran journalctl --since="2012-11-27 16:28:06" --until="2012-11-28 07:37:53" _SYSTEMD_UNIT=NetworkManager.service and pasted the results at http://pastebin.com/6e9BNvmD.  (Note: journalctl ignored --until="2012-11-28 07:37:53" but I edited out the excess lines.)

An Arch Linux forum thread regarding this is at https://bbs.archlinux.org/viewtopic.php?pid=1199706#p1199706

Maintaining this connection is important because the S12 is used as a portable Skype terminal.