Starting with kernel version 2.6.36 tuxonice has been removed from the zen-sources patchset, the high-performance linux-kernel for desktops. With the new zen-sources-2.6.38_p20110510 ebuild the maintainer of the zen-sources ebuilds started to include tuxonice into the zen-sources ebuilds in gentoos portage tree. Now the reliable suspend mechanism, tuxonice is known for, is again easily available on genttoo systems with zen-.sources. Thanks Markos!
A Gentoo user now can choose if he wants to have zen-sources with tuxonice or not. To get zen sources with tuxonice one just has to include the tuxonice USE-flag into his /etc/make.conf and emerge zen-sources afterwards. Then one has to configure and compile the kernel as usual.