This post's subtitle rewrites something Hamlet said: How all occasions do inform against me...
Prose discloses. However much you think you're hiding, the way you write, the grain of your language, gives away all sorts of things about you. Are you a snob? Do you think you're better than other people? Are you terrified of self-assertion? Are you vindictive? A prude? A prune? Your prose will tell.
This is because writing is consciousness. Your writing is your own peculiar, particular, specific, inimitable, personal, individual, consciousness.
Good writers to a large extent control the effects of their consciousness. They are aware of writing's disclosing power, and they decide what and how they want to disclose.
A number of writers said useful things about writing in general, and writing for blogs in particular, in a recent symposium at 10 Zen Monkeys. 
One of them quoted Italo Calvino:
Writing always presupposes the selection of a psychological attitude, a rapport with the world, a tone of voice, a homogeneous set of linguistic tools, the data of experience and the phantoms of the imagination - in a word, a style. The author is an author insofar as he enters into a role the way an actor does and identifies himself with that projection of himself at the moment of writing.
Note the language of control: A good stylist selects an attitude, decides how she wants to connect with the world, enters into a certain role, projects a chosen self... None of this implies inauthenticity. It points to an informed and strategic deployment into prose of an aspect of one's consciousness pertinent to the subject matter at hand. Of course, if you're writing a novel, you're explicitly taking on an alien consciousness; but if the form is the essay or blog post, you're shaping your own consciousness into a mode of address intended to pull a reader into your world.
As another contributor to the Zen Monkeys symposium writes,
good prose infuses nonfiction, whether criticism or journalism or essay, with an almost poetic and emotional sensibility that ideally reflects in style and form the content that one is expressing.
Not emotion for emotion's sake -- histrionic, manipulative writing alienates - but an emotion appropriate to content, and, more broadly, a verbally intriguing sensibility that attracts and holds the reader.
This same contributor worries, though, that the rapidity of web culture, and its pressure on writers to have opinions about everything,
is not an encouraging environment from which to speak from the heart or the soul or whatever it is that makes living, breathing prose an actual source of sustenance and spiritual strength.
But UD/ SOS isn't so sure. Blog writing has a cumulative effect. Over time, on the strongest blogs -- Andrew Sullivan 's, for instance -- many posts create a rich persona, a complicated and even moving human individual. UD has watched Sullivan struggle with his religious faith over many years on his blog, so that with each new post on his doubts, the fragility and intricacy of belief is further illuminated.
Along the same soul-crushing lines, another contributor worries that
Oscar Wilde would be just another forlorn blogger out on the media asteroid belt in our day, constantly checking his SiteMeter's Average Hits Per Day and Average Visit Length.
Again, UD has her doubts. As does yet another contributor, who writes that
The profusion of written thoughts and emotions [on the web] is certainly overwhelming, but the true writer is likely to be a selective and highly skillfull reader, and thus has many jewels to select from, to be inspired by, to be wowed by, and to otherwise cause the truly ambitious to carry forth with passion and a whip-smart disposition.
Again, this is Calvino's point: selectivity rules. Wilde, a supremely gifted writer and reader, would surf the web like a master, steadying himself on a few first-rate blogs and learning from them. Since he was a narcissist, he would certainly check his SiteMeter more than once a day, but from it he would come to understand the nature of his audience, and with this knowledge, he would sharpen his prose yet more, carving out for himself a readership worthy of his efforts. Rather than inform against him, Wilde's on-line prose would probably have elaborated an enormously appealing consciousness, and informed his readers in the way the world looks to a living, breathing soul.