What is the Elo of the Mac Book chess engine at top strength? This will always have to be an approximation, but on a Mac Book Pro with the 2.8 GHz processor, plugged in, and with the engine set to the maximum strength setting, what Elo is it? I don't have direct access to the engine as far as I know, so I can't set it up to run tests against other engines, and doing that manually would be a real pain in the neck. Does anyone know what its Elo is, or if there is another way I could find out? This is assuming that Apple wrote its own chess engine and didn't just use one that was already out there (there are plenty of free, open-source chess engines). I'm also assuming that they don't rewrite the engine with each new version of Lion.

I was really surprised to see that there was no information about this on Google, and that nobody was even curious. Chess Titans speculation is out there but there is very little on the Apple program, which is surprising, because as an expert player I can handle Chess Titans, but Apple's program is much more challenging.  

I will upvote guesses, but for the best answer I'd like either the actual Elo (unlikely, since that information probably doesn't exist) or a very educated guess based on tests or some other comparison to other existing chess engines.

For those curious about comparing chess engines or chess computer strength in general, check out the Wikipedia article chess engines.
The Mac chess app is based on the Sjeng engine.

A page on the Sjeng website says:


  Sjeng is probably a bit weaker in bughouse than it is in crazyhouse.
  Most Sjeng's on the FICS have a rating of about 2000 points in
  bughouse, with a top of over 2200 points.
  
  For standard chess, Sjeng's rating is probably about 2450 ELO [sic]. In
  suicide and losers chess Sjeng beats all but the very best humans, and
  will beat non-specialized programs easily.


So, according to the makers of the engine Apple uses, the Elo is around 2450 in standard mode.