Unfortuantely it turned out that the Webkit endian issued ran deep into the design of the JIT engine, so getting the issues ironed out took quite a while longer than I had expected.

The good news is that OWB+JIT is now successfully running simple Javascript programs as native PPC code. The bad news is that if I need to iron out every single endian issue, it'll take forever before I'm done. So my current plan is to try to leave some of the endian bugs intact, and instead work around them in the PPC specific part of the code. The advantage of doing it that way is that, if it works, it will take a lot less time to do. The disadvantage would be a negligible (probably less than 1%) performance loss.

Here is a phone camera shot of the first Javascript test program that successfully ran through the JIT. It's a simple page with a counter on it that increments when you move the mouse over the counter.