Again, I must offer a disclaimer that I only read a fraction of the total source code, but I would assume it would involve similar use-cases to sqlite [1]. For example, IIRC, the Firefox web browser uses (used?) sqlite for storage. However, reading over the list I just referenced, I must correct myself and say that for most websites, you would probably be ok in using it; however, this seems to be an embeddable replacement for mongodb, which is typically used for high-traffic environments anyway. I'm coming more from a background of high-traffic sites with large datasets, so I typically rely upon more tailored solutions, but I should be careful not to see everything through my own narrow perspective!

[1] http://www.sqlite.org/whentouse.html