Apparently, you can now use Twitter to put a prayer in the Western Wall. A colleague of mine wrote about what, exactly, is wrong with this - calling it "Fast Food Judaism." Quick and easy religion which might feel satisfying at the time, but ultimately is unhealthy for you. Pretty good analogy, if you ask me (and I do love a religious analogy).
I'd go a step further than he does, though. He does allow for the value, in a limited way, of putting prayers in the wall (for those who don't know, the Western Wall in Jerusalem is sacred, and many people write prayer on slips of paper, and put them in the cracks of the wall). Let me preface this by saying that, like him, I love the Wall - I've always found it incredibly powerful to be there, and I am always drawn to return to it, whenever I'm lucky enough to be in Jerusalem.
Put the whole idea of putting a note in the wall just runs counter to what I believe. No matter how people try to justify it (and some just accept this as literal fact), the implication is that God hears our prayers (reads our prayers?) better when they are put there. If I ask God for health, or happiness, or a new car, but I do it here in Tampa - well, that gives me a 20% chance of getting what I want. But, if I stick that prayer in the Kotel (the Hebrew word for "wall"), then it jumps up to 80%. Maybe 90%, if God's running a special that week.
There is a very fine line between religion and superstition. One of the signs that you're crossing that line is if you ever say "this prayer/ritual/rite will work better if it's done in this way/at this time/in this place." To use one of my own favorite (and well used) metaphors, God is not a Cosmic Vending Machine, requiring only that we learn which buttons to push, and in what order, to get what we want.
Of course, this can get overstated - holidays are special times, and the Wall is a special place. Finding sanctity in some times and places isn't inherently superstitious. But, believing that God will react differently, in a literal sense, in those times and places is. Are there ways to do the "note in the Kotel" thing that don't cross that line? I'm sure that there are. But, when people think that Tweeting "please give me a pony" is, in any way, better than an authentic, personal prayer, then I think we've crossed a line.