It look like it will be possible in the future to easier upgrade JavaME on Nokia phones. It would be great if it works in a similar manner as in JavaSE for windows!!
****** from Forum Nokia Developer Newsletter *******
New Versioning Scheme for S60 Java RuntimesStarting with S60 3rd Edition, Feature Pack 2, Java implementations will be versioned separately from the underlying S60 platform. All Nokia S60 devices come equipped with an implementation of the Java Platform Micro Edition (Java ME), also known as Java Runtime for S60 (also known as JRT). For example, Java Runtime 1.3 for S60 (JRT 1.3) is the latest version shipping with the Nokia 5800 XpressMusic, a device based on S60 5th Edition. (In fact, the exact version returned by Java environment is 1.3.4.). Developers can check the Java Runtime version by using the standard mobile information device profile (MIDP) system property microedition.platform. For example, with the Nokia 5800 XpressMusic, the system property would return:
For details of the version features, download two Forum Nokia Wiki release notes.
Java Runtime 1.3 for S60 release notes.
Java Runtime 1.4 for S60 release notes
To learn how to create a MIDlet for asking the property and parsing the individual details, download this Forum Nokia Wiki article.
Learn more about Java Runtime for S60 releases and their versioning from this Forum Nokia Wiki article.