The latest update to NetworkManager-0.8.0-11.git20100503.fc13 breaks my setup. I have IPv6 disabled (no kernel module, set as "Ignore" in NM). But NM now deactivate WIFi connection as there is no file /proc/sys/net/ipv6/conf/wlan0/accept_ra on my system. The correspondig lines from log are there:
May 6 11:59:59 XXX NetworkManager: <warn> (wlan0): error reading /proc/sys/net/ipv6/conf/wlan0/accept_ra: (4) Failed to open file '/proc/sys/net/ipv6/con
f/wlan0/accept_ra': No such file or directory
May 6 11:59:59 XXX NetworkManager: <info> (wlan0): device state change: 7 -> 9 (reason 0)
NM should not deactivate device if there is no /proc/sys/net/ipv6/conf/wlan0/accept_ra file and IPv6 is set as "Ignore" in NM config.
*** This bug has been marked as a duplicate of bug 588814 ***