Apple's flipped the switch on extending iTunes preview clips to the totally revolutionary length of 90 seconds. Only songs that last for two and a half minutes or longer and a limited number of artists are benefiting from this change -- which seems to be of Apple's unilateral doing -- and it's only effective in the US iTunes Store. Trust us, we checked our UK accounts and were met with those mediocre, entirely unsatisfying 30-second previews on everything. We reckon there's still a little more intrigue left in this tale, particularly when it comes to propitiating the record labels and negotiating international deals, but we'