Periodically NetworkManager seems to hog the CPU for minutes at a time. Snapshot:

  PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND           
                                         
 2128 root      15   0 36516 2444 1356 S 12.0  0.2 138:15.30 NetworkManager    
                                         
 2597 sd        15   0  598m 311m  73m R  0.7 31.1 256:16.31 firefox-bin       
                                         
 2224 root      15   0  579m 181m 9216 R  0.3 18.1  48:07.32 Xorg              
                                         
 2332 sd        15   0 15576 1264 1000 S  0.3  0.1  13:52.50 tpb

As I write this, it's gone quiet again. But as you can see from above it adds up
over time. (uptime 2days above)

It doesn't seem related to network activity or dropouts or changing network.

This is a new problem (since I upgraded from FC6? Can't be sure, but seems recent)

This machine has an atheros chipset. I'm using the madwifi driver from livna:

kernel-2.6.21-1.3228.fc7
kmod-madwifi-0.9.3.1-1.2.6.21_1.3228.fc7.i686.rpm
madwifi-0.9.3.1-1.lvn7.i386.rpm
NetworkManager-0.6.5-7.fc7