This is the brilliance of Instapaper, not that it lets you read a website without clutter, that it lets you queue up webpages to read later. Yes, in theory, del.icio.us let you do this, bookmarks let you do this, but in practice, who knows if that page will still be there, del.icio.us has no smooth way to differentiate your reading queue from longterm links other than by tagging them. Too much maintenance. Instapaper is the equivalent of emailing yourself every article you ever wanted to read, and then auto archiving it once you have read it. Except it's only one click.
What we need is a more generalized media queuing platform that.. or maybe like OSX's concurrency queues. An orderly one-clickable series of queues we can create and maintain to organize and streamline our media consumption.
Twitter as a solution for a specific subset of this problem
As an aside, I used to subscribe to the RSS of any blog of interest that came along, there are two problems with this mode of functioning (1) It's not always trivial to find an rss link, sadly. Worse, some websites don't have RSS at all, since they're more or less static -- until they change. (2) Personalities and Products don't always update their blogs with what's really important.
So now, Twitter has become my defacto bookmarking solution. I just follow any site/person/product/business and then if for some reason they ever do anything important i should know about, sooner or later it will pop up in my twitter feed .. and if I don't notice it, i guess it was too transient to pay attention to.
The transience of information is brought out by twitter in a way that is lost on RSS. Until I read an update, it'll stick around in GReader waiting for me to read it.. even if it's boring and useless. In twitter anything that isn't "sticky" will vanish out of the sheer hugeness of twitter updates that have grabbed mindshare.
The argument against, of course, is that Twitter means the lowest common denominator get to pick out what's important.. but lists and good twitter clients help smooth out this problem.