Sun published performance benchmark for JDK 5.0. It is around 3 times faster than 1.4.2 as per Specjbb2000, less spectacular in other benchmarks. Read it.

Do you know that now you too can contribute in developing the next version of Java - Mustang? Here is your chance. What is Sun's motivation? This definitely isn't about cost reduction. Our development costs are dominated by the back-end processes: code reviews, integration, test development, release engineering, testing, and long-term maintenance. We expect it will take significant work on the Sun side to mentor contributors and integrate external fixes. Based on other experience, we expect that this project will increase our costs, not lower them. But there are two positive benefits that we believe will outweigh the costs.

Some people have started preaching/scolding the web developers for using HTTP GET in non-idempotent manner. In other words GET is often used to change the state of the system, when it shouldn't be. And when it does, Google Web Accelerator does all unmentionable things to the web application like pre-fetching delete links, creating new records etc. This is a classic dilemma.