TUAW apparently received tips that the iPhone 2.0 firmware might ship a little later than expected, probably late June, early July. This is because of Apple’s deal with the cell carriers. Per their agreements, Apple has to give the cell carriers a chance to look at the new firmware before it can ship. This normally takes 1-2 weeks.
According to TUAW sources, the 2.0 firmware went out to cell carriers this week, meaning that they will review it for the next 2 weeks. If everything is fine with the firmware, Apple will release it to the public. Otherwise, Apple will have to fix the problems and start the process over again.