Sales data for the iPod is less encouraging, but this is also in line with Munster's January prediction that the iPad would likely cannibalize sales of Apple's lower-priced media players. iPod sales are down by 17% year-over-year, which is an even worse dropoff than what Munster predicted. However, there's an upshot to the decline in iPod sales: according to the data, many people deciding against buying an iPod are buying an iPad instead, leading to increased revenue for Apple. With an average price four times that of the average iPod, Munster calls iPad cannibalization of iPod sales "a net positive for Apple's business."
There's no indication from NPD of what effect, if any, the iPad is having on the iPhone's sales. However, it seems unlikely that the iPad is significantly affecting the iPhone's sales compared to other factors. Numerous media leaks have pretty much cemented the notion that iPhone updates are due soon, with coverage so widespread and mainstream that even average consumers must be well aware that it's a good idea (for them) to hold off on buying an iPhone until the likely update next month. Apple reportedly told police that Gizmodo's leak was "immensely damaging" to Apple for that very reason; we'll probably have to wait until Apple's next earnings release sometime in July before we know just how immense the damage has been.