It's the company's No. 1 source of revenue, driving growth that could reach 50% this year

    If you're an investor wondering whether Apple's (AAPL) latest iPhone is worth all this fuss, Bullish Cross's Andy Zaky has done you a favor. The blogger-analyst whose quarterly estimates of Apple's earnings regularly beat Wall Street's (see here and here and here) has boiled it down to the color-coded chart below:

    Note the growing red splotch that already dwarfs the iPod's revenue stream and threatens to overwhelm the Mac's, at least according to Zaky's projections (the last two data points are estimates). By September, when Apple's fiscal 2010 ends, he expects the iPhone to account for 37.4% of Apple's receipts. It might have been 40.8%, he says, were it not for the new revenue flowing in from iPad sales.

    For more charts -- and a detailed explanation of how he derived them -- check out the article Zaky posted overnight Thursday, just before he went out to join the queues for the iPhone 4.

    Below the fold: an unpublished Zaky chart showing Apple's year-over-year revenue growth, which he projects will reach 50% by September.