Even after the Mac OS X 10.5.1 system update, some users are continuing to report problems with their wireless connectivity.

According to MacFixIt, readers are reporting instances where they can initially get on their wireless networks, then might have to go through network diagnostics to get back online after losing a connection.

Other readers have cited greater reliability under 10.5.1 and the following workarounds have been discovered:

After upgrading to Leopard I also had problems with my MBP reconnecting to my wireless network from sleep. I have found that if I un-tick the 'Use wide channel' tab in 'wireless options' on my Airport Extreme (802.11n) the MBP will connect every time. The downside is my link speed goes from 300Mbps to 130Mbps but i can live with that.

and

On my Macbook Pro Core2Duo 2.33mHz, after upgrading to Leopard I too experienced the sometimes connected / sometimes not syndrome. After much digging and surfing, I found the solution that works for me on my WRT-150N Linksys router and Airport.

Force 802.11g Only … Mixed Environment just did not work under Leopard
WPA or WPA2 Security … WEP is just old and outdated, WPA is stronger and less likely to cause issues.

If you've found any problems between Mac OS X 10.5.1 and your AirPort connection or noticed a good workaround or fix, please let us know over in the comments or forums.