One of the constant points of conversation (at least it should have been if you think about it for more than a few minutes) about URL shorteners is that you, the person who’s sharing that link on Twitter or your blog or wherever, are putting a lot of faith in that site/service continuing to exist.

If you use X service and it goes out of business then all the links you’ve shared are, in essence, gone. That’s always been a looming danger and, now that has announced it’s closing its doors, we’re about to get a glimpse into just how big that danger is.

While might not have that big a slice of the market share pie. Before it was shut down it had, according to TechCrunch, about four percent of the shortening market, something it blamed Twitter for since it recently chose as its default shortening service. It had apparently been looking for a buyer for some months with no success and, failing that, had also brushed aside an overture by to import its links there by working with them on a project had tried to get off the ground before but had gotten “No thanks” responses regarding from the other URL shortening services it approached. URLs will continue to work through the end of the year and then, unless a purchase or some other deal is worked out, they’ll presumably go dark.

While everyone went a little nuts with the analysis of a five hour or so disappearance of Twitter and Facebook last week, this is actually the sort of thing that has more “lessons to learn” aspects about our use of the social web, especially when you think about all the free services we use in our lives. The danger is not in that there will be down time that keeps us from communicating on X platform for half a day. It’s in one of these services that we’ve spent considerable time cultivating for ourselves and for the brands we manage just poofing – not suddenly but over time – and then not being there anymore, leaving us to start from scratch.

That’s also the mindset I’m using to approach the Facebook acquisition of FriendFeed. It’s interesting in that Facebook finally realized instead of just adding more of FriendFeed’s functionality over time it should probably just buy it and get the talent that company already has.

While FriendFeed’s future remains unclear – there are vague statements about continuing service and such like that – it’s not going to matter much since it has yet to break into the mainstream. Content aggregation is interesting to those with a ton of outlets, those looking to streamline their reading and Robert Scoble – but it’s not a tool many people touch.

It’s actually easy to see FriendFeed languishing as its talent gets pulled into adding some of those features into FaceBook. I doubt the site will completely disappear or lose what it does, but Facebook wants that feature set on its site and not elsewhere. Real-time search, content aggregation, threaded comments – there’s some major coveting going on. So while it might continue to exist it’s unlikely to see new innovation.

Both of these stories, though, show that while we get attached to this, that or the other Shiny Object of the Moment, they’re all just transitory, their existence dependent on how valuable they are to a select group of people, whether it’s users or those looking to co-opt their technology.