Will iPhone 4S preorders melt online stores again?

One minute past midnight tonight Pacific time, Apple's next iPhone becomes available for preordering in seven countries, including the U.S., and the big question is whether Apple and its carrier partners face a meltdown similar to what happened with last year's model.

You might remember that shortly after the iPhone 4 went on sale, both Apple and AT&T's online sites ran into problems almost immediately. A deluge of eager buyers hit the two sites in the early morning, grinding the ordering process to a halt. The following day Apple released a statement saying that it had taken more than 600,000 preorders for the new device, breaking previous presale records. Shortly thereafter, the device sold out, pushing orders back days, then weeks past launch.

Making things more interesting this time around is that the iPhone 4S is launching on two additional carriers simultaneously (Verizon and Sprint), bringing the online buying possibilities up to four stores in the U.S. The phone is also launching in Australia, Canada, France, Germany, Japan, and the U.K. at the same time. By comparison, last year's device did not arrive in Canada for some three months after the launch in other countries in that same group, not to mention that buyers could only buy the black version, with the white version facing what would turn out to be a 10-month delay.

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Despite Tuesday's Apple.com downtime during the iPhone 4S unveiling, there are signs it, along with the carriers, have patched things up since last year's mishaps. Most recently there was the online presale of the iPad 2, which began at 1 a.m. PT/4 a.m. ET on a Thursday. Ship times quickly ballooned past the launch date into what Tim Cook dubbed during the company's second-quarter earnings call as "the mother of all backlogs." Even with that, the various online ordering systems held up, as did lines for the product at Apple's retail stores. If anything, one of the only big hiccups was that some early Verizon iPad 2 buyers didn't get their devices as quickly as they were promised when buying them directly from the carrier.

Before the iPad 2 launch, there was the launch of the Verizon version of the iPhone 4 in February. In a similar early morning affair at 12 a.m. PT/3 a.m. ET, Verizon's site held up despite some scattered slowdowns. Some customers did, in fact, experience problems through Verizon's site, with a company spokeswoman later saying that "most customers" could complete their orders, and that most of the issues were related to a customer's account status. Verizon later proceeded to suspend preorders for the device, saying it had its most successful first-day sales in the company's history.

Of course the big newcomer this time around is Sprint, which like AT&T and Verizon, is opening up preorders early tomorrow morning. Sprint has had other hot handsets before, but how it will handle the iPhone 4S is a big question mark. Earlier today the company began selling Apple's iPhone 4, the predecessor of this year's model.

As for whether changes have been made to any of the online systems to prepare for iPhone 4S preorders, AT&T, Sprint, and Verizon representatives declined to comment for this story. Apple did not respond to a request for comment.