“A pretty sweet solution.”

That’s how Steve Jobs has described Apple’s plan to permit the building of Web-based applications for the iPhone, while withholding a software development kit (SDK) and full access for creating native apps.

But the Apple CEO’s announcement, earlier this week, hasn’t exactly sweetened the disposition of many developers, who were expecting much more.

For a lot of these folk it’s been quite a roller coaster ride – emotionally speaking – since the device was first unveiled in January: with disappointment turning to optimism, turning to disappointment again.

Flashback to early January.

Jobs’ statements at the time emphasized that Apple would rigidly control what went on the iPhone.

“These are devices that need to work and you can’t do that if you load any software on them,” Jobs had told the New York Times soon after the iPhone was unveiled in January.

“We define everything that is on the phone.” he said. “You don’t want your phone to be like a PC. The last thing you want is to have loaded three apps on your phone and then you go to make a call and it doesn’t work anymore.”

Many read this as a statement that Apple would keep the iPhone closed to third-party development.

Fast forward four months to May 10 and Apple’s annual shareholders meeting.

At this event Jobs’ offered a more positive message, saying his company was “wrestling” with a way to support third-party development on the iPhone.

Less than three weeks later, on May 30, at the D: All Things Digital Conference near San Diego, Jobs made it official – Apple was working to open up the much-anticipated device to outside developers.

Software developers were delighted. Their sentiments were articulated by Austin Sarner, creator of Mac uninstaller AppZapper, and disc-burning application Disco, who called it “a great decision on Apple’s part.”

But such enthusiasm was short lived.

Jobs’ announcement, earlier this week, at the Worldwide Developer Conference was viewed almost as an anti-climax:

• No SDK for the iPhone

• No permission to write native apps

• Developers will only be able to create Web apps running within Safari (Apple’s Web browser that will be included on the iPhone).

Many were deeply disappointed.

“Everything seems so limited at this point,” rued Sarner, who three weeks ago was bubbling with enthusiasm.

Another developer – John Casasanta, president of Inventive Inc. – echoed those sentiments: “I would be lying if I said I wasn’t disappointed.” Littleton, N.H.-based Inventive is a maker of Mac software.

Various developers have articulated what they believe this lack of full access to creating iPhone programs will mean.

Among potential issues cited are: limited performance of apps developed solely within an “abstracted” environment, no sharing of information between applications, and size and control problems.

More crucially, some have pointed out that inability to write native apps for the iPhone could impede the device’s usefulness within the enterprise.

Some industry insiders note that using the device with customized software, such as bar code and RFID readers (as is being done with certain cell phones) can’t be accomplished with a browser interface.

They say deeper access would be required to create an app that could talk to (say) IBM or Oracle middleware using native APIs.

Analysts who cover the mobile space – such as Gartner’s Ken Dulaney – are dissuading adoption of the iphone in the enterprise.

Dulaney says the device will have numerous shortcomings for business users such as: no removable battery, multiple processors, which consume more battery life than a single one, a touchscreen and no buttons.

He submits that even if the iPhone is attractive, like the Mac, business users would prefer the BlackBerry or Windows Mobile devices, as those have more software application options.

Now with Apple’s 3rd party development program – that some see as very limiting – it’s likely adoption of the iPhone in the enterprise will be even more tardy.

For without a range of corporate applications, enterprises would essentially be getting employees a cell phone cum giant ipod, with plenty of storage for their digital music collections.