The current spec does not say that it it is legal to use autoboxing (or auto-unboxing) in array initializers (though it probably should). Curiosity got the better of me, so I tried compiling the following program:

public class Test {
    public static void main(String[] args) {
        Integer a[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
    }
}

The compiler keeled over:

An exception has occurred in the compiler (1.5.0-internal). Please file a bug at the Java Developer Connection (http://java.sun.com/cgi-bin/bugreport.cgi) after checking the Bug Parade for duplicates. Include your program and the following diagnostic in your report. Thank you.
java.lang.ArrayIndexOutOfBoundsException: -1
        at com.sun.tools.javac.jvm.Code.emitop0(Code.java:545)
        at com.sun.tools.javac.jvm.Items$StackItem.duplicate(Items.java:271)
        at com.sun.tools.javac.jvm.Gen.visitNewArray(Gen.java:1702)
        at com.sun.tools.javac.tree.Tree$NewArray.accept(Tree.java:854)
        at com.sun.tools.javac.jvm.Gen.genExpr(Gen.java:801)
        at com.sun.tools.javac.jvm.Gen.visitVarDef(Gen.java:954)
        at com.sun.tools.javac.tree.Tree$VarDef.accept(Tree.java:508)
        at com.sun.tools.javac.jvm.Gen.genDef(Gen.java:648)
        at com.sun.tools.javac.jvm.Gen.genStat(Gen.java:683)
        at com.sun.tools.javac.jvm.Gen.genStat(Gen.java:669)
        at com.sun.tools.javac.jvm.Gen.genStats(Gen.java:720)
        at com.sun.tools.javac.jvm.Gen.visitBlock(Gen.java:967)
        at com.sun.tools.javac.tree.Tree$Block.accept(Tree.java:537)
        at com.sun.tools.javac.jvm.Gen.genDef(Gen.java:648)
        at com.sun.tools.javac.jvm.Gen.genStat(Gen.java:683)
        at com.sun.tools.javac.jvm.Gen.genMethod(Gen.java:905)
        at com.sun.tools.javac.jvm.Gen.visitMethodDef(Gen.java:841)
        at com.sun.tools.javac.tree.Tree$MethodDef.accept(Tree.java:479)
        at com.sun.tools.javac.jvm.Gen.genDef(Gen.java:648)
        at com.sun.tools.javac.jvm.Gen.genClass(Gen.java:2174)
        at com.sun.tools.javac.main.JavaCompiler.genCode(JavaCompiler.java:322)
        at com.sun.tools.javac.main.JavaCompiler.compile(JavaCompiler.java:464)
        at com.sun.tools.javac.main.Main.compile(Main.java:584)
        at com.sun.tools.javac.main.Main.compile(Main.java:536)
        at com.sun.tools.javac.Main.compile(Main.java:41)
        at com.sun.tools.javac.Main.main(Main.java:32)