How would you react if you got such an sms at 7:35 am, shortly after you've gotten out of bed? I almost laughed out, but am not quite sure which reason was funnier - the sms itself or the last line with a smiley!
I completely sympathise with the victims of the blast, but surely wearing black clothes and urging others to do so is of no help! There are better and more practically useful ways to pay homage such as collecting funds (in one's college or place of work or locality) to try to relieve the financial burden of treatment of the wounded.
And as for protesting against terrorism, I don't understand this whole 'protest' concept in this situation (it may be effective in other situations, mind you) - is it to try to get the government / police machinery to function better / more effectively? Do you genuinely believe that the agencies responsible for prevention of such acts are not already working at the fullest capacity? It would be hard to believe so, given that ultimately they themselves and their families are also the targets of terrorism, more than the common public! Then the remaining lots are the common public and the terrorists themselves. Speaking of the common public, with all the media and word of mouth spreading of news, who's left in the city who doesn't know of the happening? And how many of these do you think will turn a blind eye to something suspicious? And how many of these who are in a state of 'don't care and I'm not getting in this' are going to change their minds because of you wearing black clothes? Finally for the terrorists - I think common sense begs us to believe that those who have silenced their conscience enough to commit such a dastardly act and don't fear the law even, are surely not going to succumb to a mass of public wearing black clothes!
I mean, get real! If you cannot do something practically useful, at least don't resort to such laughable means! Giving moral support to each other or the affected people is all acceptable, but make sure it reaches out to them, maybe by means of a condolence gathering like the one held at the Gateway in Mumbai in memory of the terrorist attack there.