how do this verification thing by bitcoinica will affect the price ?
Probably won't effect it that much in the short term. People with open positions that don't want to get verified will have to close, but this will be true for both shorts and longs. We probably have slightly more longs, so it might slightly decrease the price, but it won't be noticeable due to how volatile the market already is, even during "normal" times. In the long term? Nobody knows. It could attract big investors, since Bitcoin will look a whole lot less shady once stuff like this happens. In that case, it could cause an increase in price in the long run.
Still, these are just that, theories. Nobody knows for sure, but this is how I feel about the change.