It's the only way we can try to stay a step ahead. Well, hopefully you made backups before installing any patches. This is a must if you are installing any type of kernel patches. It's an extreme case when installing patches trashes things so much that you have to restore from backups, but it's worth it to take the extra time to ensure you can recover. Besides, you should have a very regular and robust backup program in place already in case of hardware failure or recovering from a compromise.
Most vendors allow for backing out their patches.
With Solaris you can use the patchrm program. With Tru64 you would run their dupatch program and choose the delete option. In order for these to work, however, the patches need to be installed properly to allow backing out. Tru64 asks during the patch installation if patches should be made reversible and gives you the option to change where they are kept. If at all possible, install patches in such a way that they can be backed out.