A US investment bank is predicting that by 2011 the largest portion of Apple's revenue will come from the iPhone.

Despite the growth of iPod - and more recently iPhone - revenue, the largest single portion of Apple's income has long come from Mac sales.

But according to Caris & Company, rapid growth in iPhone sales will be spurred to such an extent by the handset's official entry to the China market that they will match Mac revenues in 2010 and outstrip them in 2011.

Caris analyst Robert Cihra said "We continue to believe Apple has proved itself the single most innovative and profitable consumer technology company in the world and continue to see headroom for growth via both iPhone and Mac (market) share gains." (Via AppleInsider.)

This view seems to assume Apple's product mix will remain more or less stable during the period.

If the company decides it's time to move the Apple TV from a "hobby" (as Steve Jobs put it in 2007 and again in 2008) to a serious business, or to enter a new segment (ebook readers?), those revenue shares could be quite different.

Another factor would be the widely predicted arrival of an Apple tablet. If that was a member of the Mac family as opposed to an iPod/iPhone and it proved as successful as some people predict, it could see an extension of the Mac's reign as the bedrock of Apple's income.