Obviously, this is a dangerous game to play: iPad 2 buyers may be angry if iPad 3 comes out a mere handful of months later... and even if it's not true, such rumors might suppress sales of iPad 2s while people wait based on September iPad 3 rumors.
Such is the price of progress. I don't see Android customers in open rebellion because the DROID X Pro 3 Super Deluxe Gold is announced 2 months after the release of the DROID X Pro 2 Super Deluxe Silver.
Buying electronics is not an investment in an appreciating asset. It's an investment in a tool for daily use. I, for one, would rather have the option of upgrading every 6 months if my business demanded it or my budget allowed it rather than being constrained to a fixed yearly update cycle.
Anyone willing to play the endless "wait for the next version" game simply misses out on the benefits of daily use of the existing product in the meantime.