There were some known issues with the 2.6.18 kernel and the bcm43xx driver. Additionally, many important updates have been applied since 2.6.17. The wireless-2.6 patch available at ftp://lwfinger.dynalias.org/patches should be applied to the gentoo-sources-2.6.18 package if possible to obtain a working bcm43xx driver. I am unaware of any other changes that may take affect in this patch, I only know that my wireless card requires this patch to be applied before it will work. Please review this patch, and if possible, include it in the next -r of the 2.6.18 gentoo-sources.
We wouldn't consider the whole patch but would happily take individual commits which fix stuff once they are tested. Joe might able to advise here.
Don't bother, the patches in question have already been accepted for stable (2.6.18.1). When you rebase gentoo-sources against .1, you'll get the fixes for free.
Fixed in gentoo-sources-2.6.18-r1