This is great news for all webkit-based browsers including Safari and Mobile Safari.
http://webkit.org/blog/189/announcing-squirrelfish/
WebKits core JavaScript engine just got a new interpreter, code-named SquirrelFish.
SquirrelFish is fastmuch faster than WebKits previous interpreter. Check out the numbers. On the SunSpider JavaScript benchmark, SquirrelFish is 1.6 times faster than WebKits previous interpreter.
SquirrelFish is a register-based, direct-threaded, high-level bytecode engine, with a sliding register window calling convention. It lazily generates bytecodes from a syntax tree, using a simple one-pass compiler with built-in copy propagation.
SquirrelFish owes a lot of its design to some of the latest research in the field of efficient virtual machines, including research done by Professor M. Anton Ertl, et al, Professor David Gregg, et al, and the developers of the Lua programming language.
http://webkit.org/blog/189/announcing-squirrelfish/