Rather than present itself in wiki form, or as a step-by-step learning tool, each section of "Learn X" provides a brief description of a language, before providing real code examples for common tasks and operations, annotated with extensive comments.
What I like most about the site is that the descriptions are written by coders, so they tend to get straight to the point regarding each language's points of difference. For example, here's the lead for Haskell:
Haskell was designed as a practical, purely functional programming language. It's famous for its monads and its type system, but I keep coming back to it because of its elegance. Haskell makes coding a real joy for me.
Go was created out of the need to get work done. It's not the latest trend in computer science, but it is the newest fastest way to solve real-world problems. It has familiar concepts of imperative languages with static typing. It's fast to compile and fast to execute, it adds easy-to-understand concurrency to leverage today’s multi-core CPUs, and has features to help with large-scale programming.
I imagine there's a shade of bias in these blurbs, but for someone after a simple explanation on why they should investigate further, they're perfectly adequate.
Learn X in Y minutes [Official site]