The Korea Times is reporting that Apple's relationship with Samsung's supply arm is strained. According to the infamous "industry sources," (not to be confused with "people familiar with the matter"), Samsung did not participate in the development of Apple's A6 chip, which powers the iPhone 5. Instead, the company is assembling parts only. It's believed that Samsung took part in the development of Apple's A5.
Just last week, we learned that Apple added Samsung's Jim Mergard to its talented staff. Last August, Bloomberg reported that Apple and Qualcomm tried to purchase exclusive access to TSMC chip production. Considering the contentious legal relationship between the consumer products divisions of Apple and Samsung, it'll be interesting to see where their manufacturing relationship goes.