But then I switched from Java to Ruby, and half of the design patterns were completely irrelevant. And I had other problems for which I didn't have appropriate design patterns.

I think the Gang of Four book's target audience is far narrower than it's often been interpreted. It's meant for intermediate C++ programmers. People who have already run into a number of these problems that C++ doesn't really handle well, and now here's a book that helps you around those limitations.

I guess it also works well for older Java versions, but it's not universal. Many patterns are completely irrelevant for some languages, because those languages have easier ways to do that. Many languages have other shortcomings that are not handled in that book.

Maybe there's another target audience for that book: language designers. Design your language so nobody needs these patterns. Have built-in constructs that handle this stuff in an easy way for the programmer.