Fusion Drive is likely not a true hybrid drive, which packs flash and platter drives in a single enclosure, but is better labeled a "hybrid solution," since the controller and software manage where data goes.
OS X Lion and Mountain Lion -- the latter is pre-installed -- have a feature dubbed "Core Storage" that lets the operating system, and thus the user, see multiple physical drives as one logical drive.
Apple's 2011 acquisition of Israeli SSD maker Anobit probably played a major role in the development of Fusion Drive.
The hybrid does not come with any standard configurations Apple has spelled out on its website, but is an option. The company has not disclosed what it will charge for the feature. Storage expert Robin Harris, who blogs on ZDNet and his own StorageMojo, has pegged the additional charge at $250 on a 1TB drive.
Analysts were generally positive about the new iMacs.
"I thought the intro of the hybrid drive was really good, and something users have been waiting for," said Ezra Gottheil of Technology Business Research.
But both Gottheil and Patrick Moorhead, principal analyst at Moor Insights & Strategy, were taken aback by the $100 price increase. Apple usually keeps prices steady during hardware refreshes, instead swapping out newer components and adding storage space and RAM, to attract customers.
"That was surprising, especially considering how well the Windows PC makers are doing with all-in-ones," said Moorhead, referring to iMac look-alikes that cost considerably less.
The 21.5-in. iMac starts at $1,299, while the 27-in. desktop begins at $1,799.
Neither will be available soon, however. The smaller iMac, Schiller said Tuesday, will ship next month -- no firmer date than that -- and the 27-in. won't appear until December.
As of Tuesday night, Apple listed the new iMacs on its online store, but was not taking pre-orders. Apple has not said why the new desktops face such long delays, nor has it responded to questions about the inability to pre-order an iMac.
Along with the new Retina 13-in. MacBook Pro and iMacs, Apple also tweaked the Mac Mini by switching to newer Intel processors, the dual-core i5 and quad-core i7. The Mini's prices -- $599 for the lowest-priced model, $999 for one configured for OS X Server that packs two hard drives -- remained the same as the previous generation.
Although the Mac is the longest-lived product in Apple's portfolio, with the first model coming off the line in 1984, personal computers are now a small part of the company's business. In the quarter that ended June 30, Mac sales accounted for just 14% of Apple's total revenue, less than a third of the iPhone's contribution and about half of the iPad's.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter at 
@gkeizer, or subscribe to Gregg's RSS feed 
. His e-mail address is gkeizer@ix.netcom.com.
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