> If you try really hard, you can simulate pseudo threading by using  
> setTimeout. In this respect, you can perform multiple function  
> executions in what would seem to be a simultaneous fashion (even  
> though you will not get the benefits of true threading by doing so).

I was netdiving this evening and discovered that Firefox 3.5+ and  
Safari 4+ (and Chrome nightlies) do support multi-threaded javascript  
applications via "Web Workers" where one script delegates work to a  
separate OS-level thread.

https://developer.mozilla.org/En/Using_web_workers
http://ejohn.org/blog/web-workers/

Now that I've learned of it, there's some slow code I wrote a few  
months ago that I have to revisit, and I think that I might think  
about building it to support Workers where available.