A couple of days ago I saw a blog post from February (Mike Stenhouse, Trampoline Systems) that declared that (paraphrasing) “Twitter has replaced Facebook for me. It gives me everything I want from Facebook: Presence (stream from my friends). But on Facebook, I have to login a few times a day – their walled garden. But with Twitter: 24/7 Presence!”
What is the numinous appeal of Presence!
Is it a kind of love? Entertaining distraction? Sense of connectedness? The emerging Global Brain? Celebration of both uniqueness and common humanness?
Why? 20 -100 messages in a day (more?) from 10 different people (more?), some close, many not, some brilliant, many not. Why is this so comforting, stimulating, welcome?
Well, for one thing – it is attention from people I care about (and maybe some others) that requires absolutely nothing in return. Pure appreciation. I see it, laugh, nod, puzzle, or ignore it because, y’know, I’m really in the middle of something else – in fact in the middle of several things, and I have only so many neurons. But fine, keep it coming – feed my spare cycles – and soul – with quirk, you-ness, and relationship.
Is this what it is? (I’m still figuring it out.)
100 Trillion Connections 
I think presence is well, more, nuanced. I think twitter is too much noise, not enough signal, as you mentioned.
Presence is really about being eminently findable.
I talk about the difference between viral and organic marketing on an ongoing basis to my clients and blog readers. Twitter is viral, it takes advantage of my time to deliver your message, whether or not its relevant. Good, findable blogging is organic, it provides value (hopefully) that I’m looking for when I’m looking.