Certainly on the south coast of the UK this morning many of the stores have the new iPads in stock. Comet have all models and most of the mobile network stores have them for sale.
There seems to be a lot less interest in the new model than there was on the iPad2. Personally I cannot see any new features I need in the new model that make my iPad2 less usuable.
Wait until you you see an H264 HD clip or movie on the Retina screen and then say 'I cannot see any new features I need.....'