Apple Inc. (Nasdaq: AAPL) has just over a week left to deliver its promised software development kit for the iPhone, a move that some analysts consider crucial if the market for the iconic gadget is to continue to evolve and generate revenue for the vendor, carrier partners, and developers themselves.

In a letter on the Apple site late last year, Steve Jobs promised that the code, which will allow third-party developers to write applications for the iPhone, would be available "in February." The Mac maker hasn't yet responded to questions about when the SDK will be available, but it's clear that anticipation about the release is running wild in the wider Apple community. (See iPhone to Get Third Party Apps.)

Last week, a developer caused a major stir by claiming that the SDK would be released with the latest iPhone firmware update but later retracted his claims, saying he "lied." The excitement around an SDK launch is understandable, however, since it would make the iPhone a far more open development platform than it is now.

"It is an absolutely critical next step in revitalizing the iPhone, particularly for the European market but also for the American, too," says analyst Ben Wood at CCS Insight .

Like everyone else Unstrung spoke to, Wood isn't exactly sure when Apple will launch the SDK, noting that Jobs and company -- as with most things Apple -- have managed to keep up a veil of secrecy over the code's debut. He notes, however, that a lot of developers have been very tight-lipped about its arrival recently, which he believes may suggest that "rather a lot of people are working with it."

Ironically, the mass-unlocking of the iPhone since its launch last June may have helped Apple's application chances, "rather by luck than by design," Wood chuckles. "There's a wealth of apps out there already working with unlocked iPhones."

The iPhone is an attractive platform for developers because of the access to its user base through iTunes, something Nokia Corp. (NYSE: NOK) and the other major cellphone vendors can't really match. "Apple provides a unique way to monetize applications through iTunes," Wood says.

Carriers are unlikely to be complaining, either, if a flood of new applications helps the iPhone maintain its record as a data-revenue records buster. Last month, T-Mobile International AG suggested that iPhone users download up to 30 times the amount of data its other users do. (See iPhone Data Booms at T-Mobile.)

Some analysts stress, however, that the SDK does need to arrive soon if Apple is to continue to hold sway over waiting developers -- "particularly in markets like mobile handsets where [other] agreeable and profitable partner options are readily available," reckons Charles King, principal analyst at Pund-IT Inc.

"Commercial success depends on grabbing customers’ hearts, but to achieve that, vendors must first gain the minds and trust of developers," King says.

Adding to the pressure, Google (Nasdaq: GOOG) is now moving strongly into the mobile market and has had some form of Android SDK out there since November. "Google understands that [developer] lesson full well. How well Apple understands it is unclear, but unless the company delivers its iPhone SDK in a timely fashion, it may risk a failing grade among key developers," says King. (See ARMed Android.)

Other analysts, however, cast Apple developers as the Snow White of the coding world, willing to wait, wait, and wait some more for Prince Charming to come. "There is lots of time, and Apple developers will wait for anything Apple," suggests ken Dulaney at Gartner Inc.

Apple might be able to claim coolness over its rivals, but it doesn't yet have numbers. Apple recently boasted that it has sold more than 4 million iPhones. In contrast, U.K.-based operating system developer Symbian Ltd. unveiled its shipments last week, saying more than 75 million handsets with its OS onboard shipped in 2007. (See Symbian Passes 75M Mark.)

— Dan Jones, Site Editor, Unstrung