Because "signing" comments is not customary here, doing so signals a certain aloofness or distance from the community, and thus can easily be interpreted as a passive-aggressive assertion of high status. (Especially coming from Luke, who I find emits such signals rather often -- he may want to be aware of this in case it's not his intention.)
I interpret Silas's "Not necessary" as roughly "Excuse me, but you're not on Mount Olympus writing an epistle to the unwashed masses on LW down below".
I saw lukeprog's signing messages as minor noise and possibly a finger macro developed long ago, so I stopped seeing the signature.
I'd be dubious about assuming one can be certain (where's the Bayesianism?) about what someone else is intending to signal, especially considering that it's doctrine here that one can't be certain of even one's own motivations. How much less certain should one be about other people's?
I would add some further uncertainty if one feels very sure about the motivation driving a behavior that's annoying.
Singularity Institute desperately needs someone who is not me who can write cognitive-science-based material. Someone smart, energetic, able to speak to popular audiences, and with an excellent command of the science. If you’ve been reading Less Wrong for the last few months, you probably just thought the same thing I did: “SIAI should hire Lukeprog!” To support Luke Muelhauser becoming a full-time Singularity Institute employee, please donate and mention Luke (e.g. “Yay for Luke!”) in the check memo or the comment field of your donation - or if you donate by a method that doesn’t allow you to leave a comment, tell Louie Helm (louie@intelligence.org) your donation was to help fund Luke.
Note that the Summer Challenge that doubles all donations will run until August 31st. (We're currently at $31,000 of $125,000.)
During his stint as a Singularity Institute Visiting Fellow, Luke has already:
As a full-time Singularity Institute employee, Luke could:
If you’d like to help us fund Luke Muehlhauser to do all that and probably more, please donate now and include the word “Luke” in the comment field. And if you donate before August 31st, your donation will be doubled as part of the 2011 Summer Singularity Challenge.