Mac OS X WiFi Problems Since Last OS X Update

I haven't done much poking around the Mac OS X discussion boards on this issue yet. But, it seems like both my Intel Macs have been having problems working with two different wireless LAN (WiFi) Access Points (WAP) since the last Mac OS X update. The two WAPs are from different manufacturers.

The problem is either no packet reception or lost packets. By, no packet reception, I mean that the Mac does not only not get packets it does not register them as lost. This can be seen while pinging another device. Ping does not report anything for many seconds (say 10 to 15 seconds) and then starts reporting but does not show any lost packets during those 10 to 15 seconds. The other problem is dropped packets where ping stops receiving packets, starts up again, and then reports lost packets correctly.

It looks like the problem shows up when WiFi security is turned on: Either WEP or WPA2. The problem is much worse using WEP compared to WPA2. The problem appears to disappear completely if WiFi security is turned off. The WAPs themselves work fine. Non-Macs (Windows PCs, Pocket PCs, and iPod touch) all work fine with these WAPs with WEP or WPA2 turned on.

If anyone has any tips or information about this or related Mac OS X WiFi problems, please let me know.