Available earlier than we'd initially expected, iHome's replacement for its sweet spot iP9 model has arrived in stores already: the iP90 ($100) is the first major evolution of the company's classic clock radio design to appear in a long time, utilizing a sleek new shape and finally discarding the dials that used to be located on top of virtually every wide-bodied iHome unit. A new collection of clear rounded square buttons are found on top, illuminated…