FULL PRODUCT VERSION :
java version "1.6.0"
Java(TM) SE Runtime Environment (build 1.6.0-b105)
Java HotSpot(TM) Client VM (build 1.6.0-b105, mixed mode, sharing)

and

java version "1.5.0_06"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.5.0_06-b05)
Java HotSpot(TM) Client VM (build 1.5.0_06-b05, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
MS Windows XP SP 2

A DESCRIPTION OF THE PROBLEM :
The method Thread.getStackTrace() returns different results when executed on JDK 1.5 and JDK 1.6.

on JDK1.6 the stacktrace starts with the element
[0] "java.lang.Thread.getStackTrace(Thread.java:1426)"
...

on JDK1.5 the stacktrace starts with a different element
[0] "java.lang.Thread.dumpThreads(Native Method)"
[1] "java.lang.Thread.getStackTrace(Thread.java:1383)"
....

I think the problem is introduced with the lines

// Don't need JVM help for current thread
return (new Exception()).getStackTrace();

that are new in JDK 1.6 version of Thread.getStackTrace(). Seems like Throwable.getStackTrace() and dumpThreads return different results.

REPRODUCIBILITY :
This bug can be reproduced always.