According to Sun, there are over 6 million Java developers on the planet, and over 10,000 of them are working in mobile software development (to be honest, I think this number should have an additional zero in the tail, because I don't think only less than 0.01% of world's Java developers are working on software for mobile devices!), so having a JVM for the iPhone and iPod touch would ease the development of Java applications for both these devices.
At this time, there is no additional detail about the upcoming JVM available, but Sun officials said it should arrive "as quickly as possible".