To expand on this a bit more: while all three implementations are "Clojure", since Clojure is a hosted language (i.e. doesn't specify/implement its own VM) and embraces this fact, there are subtle differences between the various implementations. Some of these differences could be viewed as "bugs" and should eventually go away (e.g. cannot use macros at runtime in CLJS), but some are inherent to the platform (e.g. how do you convert a string to an integer?).
Originally, if your code was simple enough and didn't touch any of the parts that were different between the implementations, then you could simply run the same code under Clojure, ClojureScript, and ClojureCLR. If it was even mildly involved, though, you'd have to write separate implementations for each.
Then the CLJX project came along. It introduced the `#+clj` and `#+cljs` forms that could be used to specify code that should only run under Clojure or ClojureScript respectively. For Clojure v1.7.0, the goal is to implement something similar in the core language. At first the plan was to simply adopt the CLJX forms directly, but as of 1.7.0-alpha6 there is this new concept of a conditional reader.
Ultimately, as a beginning Clojurist the impact to you should be small. Eventually, if you are looking to write libraries to be used across both Clojure and ClojureScript, this will be useful to reduce the amount of duplication in your project. As you move towards the heights of advanced Clojure usage, though, this turns out to be a very powerful concept that could potentially be useful for a wide range of applications.
Since the sensorship is beyond what Google's founders had expected. Even we native Chinese had not expected that then.
However, given they have invested so much on the Free Music Plan, and the market was rewarding, why, all of sudden, they pulled their feet? And risking of losing the world's largest and emerging market?
Though, I agree there are multiple causes about that. But simply thinking they pulled because they were losing ...
The government is made up of people. After living in China for a while, you soon find some Chinese people are friendly to your face, but are monitoring your emails thru your ISP, or tracking your movements around the city, or arranging for a breakin at your apartment. And these are young Chinese, just doing what their seniors showed them. Young Chinese don't have the concept in their minds that internet blocking harms innovation, and will do the same in government when they replace their elders.
At the very least I could see myself using it in the browser for development.