The path to a stable Ruby 1.9 has been long. Almost a year ago, 1.9.0 was released. This turned out to have been less than stable. The core library has grown by many hundreds of methods since then. And, probably more significantly, people have started using 1.9 for real, and they've discovered rough edges that needed to be fixed. In particular, the multinationalization support, which is incredibly ambitious, turned out to be hard to use for library writers. James Edward Gray II was probably the first to bump into this as he updated his FasterCSV library (now part of core Ruby) to handle any encoding supported by Ruby. His problems lead to a lot of discussion, and eventually to an entirely new concept inside the interpreter. And as a result, the core team have decided to slip the release of 1.9.1 by at least a month while they investigate other encoding-related issues lurking in the libraries.