[meta] Description text in the url of a post?

[zimmyhoo]

So after the post number, there's a few words: for example, the post: "What's your favorite chapter(s - one isn't enough), and why?" has a url of: gunnerkrigg.proboards.com/thread/2068/favorite-chapter-why.  Another: "Why Gunnerkrigg Court is awesome. post your reasons here!",  gunnerkrigg.proboards.com/thread/2059/gunnerkrigg-court-awesome-post-reasons.  "I made something maybe fanarty and I wish to show it off." gunnerkrigg.proboards.com/thread/2075/fanarty-show-off

I'd guess that this is a built-in feature of proboards?  It just seems uncannily intelligent for something so unnecessary. 

[Gotolei]

I think it just takes the title and removes common words and formatting.

A large number of forums do this. I think they're even used as the primary identification for SMF2.

Pretty nifty, it gives a nice bit of foresight when the link is hovered