Politics in the Zeros shows that the INS registration/detention debacle is being repeated in Houston and Cleveland, although he notes (and quotes) that "fears raised by the detention of hundreds of foreigners last week could discourage future turnout for a registration process designed to detect potential terrorists, Muslim leaders and immigration lawyers are warning."
Hmm... let's get a little Machiavellian here. What if this is the entire point? Sure, this is largely due to INS screwups, but this sort of thing is pretty predictable... both the mobs of people that show up during the last day and the panicky response. It was the White House that was behind this whole thing in the first place, however, and it's not outside the realm of possibility that they were able to predict that the overwhelmed INS would start detaining people wholesale. In fact, it's pretty likely. More to the point, however, is a related question:
What if they also knew that it would mean that people wouldn't show up to be registered? What if that was the point?
After all, if immigrants don't show up to be registered, then they can be detained and/or deported free and clear; and they're certainly not going to show up if they think they'll be arrested whether they're abiding with the (contradictory) INS regulations or not. Sure, most people will be let out, but each immigrant will ask themselves "will I be let go" and will probably say "I can't take the chance". If that's the case, though, then the White House will find itself able to instantly and easily deport any and every immigrant from a Middle Eastern country that they wish without needing to find a pretext first. Anyone in the Bush administration could point, nod, and the guy would be on a plane later that day.
Sure, it's quite possible that this was never the intention. Still, people should be careful not to assume that there's no manipulation going on. While I believe that this administration is dangerously deluded on many important issues, it has demonstrated that it can and will do whatever it takes to get what it wants, and is quite able to employ some rather devious tricks to that effect. This could be one of them, and to assume that "there's no way they'd ever do that" is terrible naivete.