The sources seem to be part of the system as in
Code:
emerge -pvuD system
which you get when you do
Code:
emerge -pvuD world
You'll probably need to mask them out. I don't suppose you'll need the sources to build the kernel, because the linode people create the kernels for us. But, some packages may require the sources to build. In that case, you'll need them to build that package. But, you'll probably have to configure a new kernel too.
Try this to make it out...
Code:
echo ">sys-kernel/gentoo-sources-2.6.15-r1" >> /etc/portage/package.mask
emerge -pvuD world
cheers