Reading Between the iPhone OS 4.0 Lines

A very good analysis by John Gruber, of the main features of iPhone OS 4.0: multitasking and iAds.

I gave a try to iPhone OS 4.0 and dug into the documentation since we have access to the developer preview; the OS is already pretty mature. The multitasking implementation however, is more collaborative than preemptive, it will requires a good software design and expertise to make an app a good citizen. If you don’t master memory management, threading and profiling, I suggest you start training now.