Both Best Buy and Radio Shack will offer the iPhone 4 on launch day, according to a new report and a series of Twitter updates, respectively. Citing a trusted unnamed source, Engadget reports that Best Buy will be offering the next-generation iPhone at launch, and that stores will apparently have no less than 45 units on hand—30 for the higher-capacity 32GB model and 15 of the 16GB units. Additionally, Radio Shack has confirmed via its Twitter…
