TuxOnIce has a long feature list, including the ability to cancel hibernating or resuming by pressing Escape, image compression to save time and space, a versatile plugin architecture, support for machines with Highmem, preemption and SMP.
The TuxOnIce website (this one) and mailing lists provide support for dealing with issues arising. An IRC channel #tux-on-ice has been created on irc.freenode.net, where people may be able to help you with problems.
The primary author of TuxOnIce is Nigel Cunningham. A huge thanks must also go to Bernard Blackham, Florent Chabaud, Pavel Machek, Gabor Kuti and Michael Frank along with many others who have tested and contributed to the development of TuxOnIce.
You can get the source packages for the TuxOnIce kernel patch and tarballs for the userui and hibernate script from the downloads page.
Git trees can be found on GitHub.
TuxOnIce is included in all Sabayon flavours.
It's been quite a while since the TuxOnIce website was updated, but the patch hasn't fallen into disrepair. It has been quietly maintained at Nigel's account on Github, together with the Userui and Hibernate script packages.
Now, Nigel has begun work toward a 4.0 release. The major new functionality in this release will be support for incremental images. The idea is that you hibernate once, per normal. When that cycle resumes, the image is retained and the kernel starts tracking which pages of memory have changed since the image was written. Then, when you next want to hibernate, a much smaller 'incremental' image is written and you power down much sooner. Speed in writing the image is not the sole advantage, however. Perhaps more importantly, you'll also get less wear and tear on your storage device, aiding its longevity. The new functionality is still being written, but watch out for betas (Lord willing!) in the near future!