Apple has recently had massive leverage on the NAND memory market and has in the past caused issues for other manufactures wanting to use flash memory in their products.
According to AppleInsider, Apple is once again causing supply issues across the industry of flash memory. Citing a ThinkEquity Partners report on the NAND flash memory market the rumour site writes that Apple has purchased Samsung's entire available supply of NAND flash. This has subsequently caused Samsung the world's largest producer of NAND flash to put it's chips on allocation until April 2009.
Apple uses NAND flash chips in it's current iPod nano, iPod touch and iPhone models.