This has been tested on 2 different machines with different hardware (other than the ipw2220 wireless adapter from Intel). When using the gentoo net/wireless scripts the "txpower" is set to auto, but this always makes it 255dBm on the ipw2200, which causes the interface to loose it's connection with the associated AP after a short time (from minutes to hours). It can be fixed by setting the default value in /lib/rcscripts/net.modules.d/iwconfig on line 692 to fx. 20 instead of auto. This is probably an error in the ipw2200 module (all versions apperantly) - tried the one supplied with the kernels (2.6.14 and 2.6.15) and the gentoo ebuild one - same error.
You forgot to mention which version of the ipw2200 driver, which version of wireless-tools, which version of baselayout, which kernel version etc. you use. You also didn't provide any information in form of output from the commands you've based this information on, nor did you provide any details about your network configuration in /etc/conf.d/{net,wireless}. Please include the output of `emerge --info`, state which version of the affected packages you use - and provide output of the commands that made you conclude there is a problem. After providing us with the basic information needed in order for us to analyze your problem, please reopen this bug report.