First of all, it's worth noting that Nokia has introduced a new naming scheme for Java platform - "Starting from S60 3rd Edition Feature Pack 2 Java Runtime for S60 is versioned separately from the underlying S60 Platform with aim to provide more frequently new Java versions to the market. Key drivers for that are for example faster time-to-market for new features and a possibility to update Java Runtimes for S60 independently in the future via Nokia SW Update." IMHO, it's a very good decision - the concept is very similar to e.g. Sony Ericsson Java Platform 8 (JP-8) or ealier versions. Currently published versions include Java Runtime 1.3 for S60 (JRT 1.3) and forthcoming Java Runtime 1.4 for S60 (JRT 1.4).

JRT 1.3.x is in use in the Nokia 5800 XpressMusic (sw 20.0.012 onwards) and includes some new features like MIDP security prompting enhancement (a possibility to select the security setting, when the prompt is shown), popup textbox, freely resizable fonts, support for new system property "com.nokia.mid.msisdn" to retrieve the MSISDN, Nokia UI API 1.2, orientation support for Location API (JSR-179) if device has magnetometer hardware, forcing certain orientation by using "Nokia-MIDlet-App-Orientation" JAD attribute, support for downscaling of Canvas graphics.

JRT 1.4.x is in use in the forthcoming Nokia N97. It's very nice to see Mobile Sensor API (JSR-256) support (supports accelerometer, battery charge sensor, charger state sensor, network field intensity sensor). Now you can access sensors natively in Java ME like it's done in C++ (sensor framework) or WRT widgets / Flash Lite (Sensor Service API) and don't need "Multi-Language Programming". The API came to the platform quicker than I expected. JRT 1.4.x includes also Nokia UI API 1.3, 9-way navigation support, 8 Mpix camera support, improved Java support for QWERTY devices, On-Screen Keypad on device with touch screen and hardware keyboard, finger usability improvements for touch screen (tap detection).

The version of JRT can be checked by using standard MIDP system property "microedition.platform". A working sample MIDlet code is available here.