Does 'Social Bookmarks' have anything to do with trust?

Not to philosophize or anything but I was wondering what is trust? I was on a website that had the classic social bookmarking links the usual suspects - MSN, Yahoo, Digg, Technorati, Del.icio.us, etc. as I scanned through the images my mind wandered to the idea of why should anyone want to check the links I have bookmarked? Other than myself or the government as part of some unknown NSA tracking scheme? The simplest answer I could come up with was "Birds of a feather, flock together". Someone who enjoys reading my essays may share the same passion and fascination for information and as such my bookmarks could offer him or her that elusive link to a site that will open a treasure of knowledge?

It took me 125 words, 575 characters to describe a simple concept in "trust" or structure in chaos. What is the market for this trust, especially since most social bookmarking is not monetized? How does one assess convergence in trust? Shouldn't trust take investment to build? Who is measuring and tracking this investment? Is this what the community refers to as "Engagement"?

I guess I am in doubt? So is social bookmarking?