Amazon (AMZN) news roundup: 1) An iPad app is now available for Instant Video, increasing its threat to Netflix (NFLX) a bit. A $79/year Prime subscription is still needed. 2) Amazon has updated its cloud music service to include a premium option featuring iTunes Match-like downloads and nearly unlimited storage. 3) Amazon is expanding its delivery locker trial (previous) to include 7-Eleven locations in Silicon Valley. 4) A new job posting suggests Amazon is expanding its mobile ad efforts.