vBulletin
 

Just curious, this could be a trade secret, but... since vBulletin isn't open source and I can't dissect the code myself, I was just wondering if anybody could fill me in on what it's doing here; When you view a thread, the URI tells me I'm viewing an HTML page, with the naming convention ####-thread-title-without-common-words.html. Now does vB actually write a new physical file for each thread, or is it parsing the thread number out of the URI and processing the request based on that?

I realize the purpose is to be search engine friendly, and the curiousity was about what way they decided would be most efficient to accomplish that. Right now, personally, I'm abusing the hell out of mod-rewrite.
-m

I am actually going to go figure out if this was truly for search engines...

It's the mod VbSEO that does this if I'm not mistaken and I can't really say how it does but as for the human friendly links as far as I have it understood it doesn't really make a difference to google (I say google because who the hell cares about the other ones?) since they do checks on content and the tags but it makes it a hell of a lot easier to see what the web page is actually about to a reader who happens to look at links.

There's other search engines?

Probably uses mod_rewrite to pull the ids out of the url and use the correct PHP files.

For SEO keywords in the URL do help.