In JDK-1.5_10 Sun changed certain undocumented "features" in jni.h such that JPype doesn't compile with this release of the JDK.
Among those are the "functions" pointers in struct JavaVM_ and struct JNIEnv_ and struct JavaVM_ alltogether.
Fortunately the official way of doing things still works so I made a patch against JPype 0.5.2.1 to make it compile again.
Unfortunately I didn't find the generator for src/native/common/jp_javaenv_autogen.cpp so I had to patch the file itself although it carries a warning not to edit it manually.
I tested my patch with JDK-1.5_10 and JDK-1.4.2_10.