Digg PHP’s Scalability and Performance - O’Reilly ONLamp Blog

Most scaling and performance challenges are almost always related to the data layer, and are common across all language platforms. Even as a self-proclaimed PHP evangelist, I was very startled to find out that all of the theories I was subscribing to were true. There is simply no truth to the idea that Java is better than scripting languages at writing scalable web applications. I won’t go as far as to say that PHP is better than Java, because it is never that simple. However it just isn’t true to say that PHP doesn’t scale, and with the rise of Web 2.0, sites like Digg, Flickr, and even Jobby are proving that large scale applications can be rapidly built and maintained on-the-cheap, by one or two developers.

Let’s not confuse the Java runtime with the language itself, I’m sure one can write “scalable” apps in Logo as well as long as the deployment is horizontal.
The truth is the comparisons are bogus, Java and scripting languages are more complimentary than competitive. Now if/when Java runtimes will add support for dynamically typed languages (the ‘Invokeddynamic’ bytecode), we’ll probably see a noticeable rise in adoption of hosted (JRuby, Jython) scripting languages within the “enterprise”, as RAS and deployment issues will no longer be the (biggest?) stumbling blocks they are now.