Currently we always return true for java.lang.Class.desiredAssertionStatus and swallow -ea/-da/-esa/-dsa command line arguments. Some programs (the X10 compiler for one) fail assertions during their execution and therefore returning true causes these program to die with an AssertionError. We should implement this properly so that we are equivalent to a standard JVM.
This bug replaces bug 1147437 on sourceforge which has more details and poses the unanswered question as to whether we want to move from VM._assert to assert:
http://sourceforge.net/tracker/index.php?func=detail&aid=1147437&group_id=128805&atid=712768