The Big Thing at Apple’s 2012 Developer Conference

Here’s the thing about Apple’s Worldwide Developers Conference: It’s not the huge deal it used to be — not for Apple’s top line, anyway.

Until last year, Apple used it three times in a row as the launch pad for new iPhones. And because the iPhone is the top-selling product in Apple’s portfolio (and among the most profitable), that made WWDC arguably Apple’s most important event of the year.

Recently some subtle things have shifted, though. Instead of unveiling new iPhone hardware at WWDC last year, Apple previewed the upcoming iOS software. Apple also launched iCloud, a service that will stretch across all of Apple’s products, providing storage and other features. In the past, Apple has also spent time talking about Mac software.

So what’s likely to be the big takeaway from this year’s WWDC? Think margins.

Here’s why: A big part of the iPhone’s value is wrapped up in the love and loyalty it inspires in customers. Many carriers are willing to subsidize iPhones to the tune of $450 up front because iPhone customers (a) stick with their carrier longer to buy more accessories and other services, (b) buy bigger data plans, and (c) need less hand-holding.

What makes that possible? Software and services. They drive the loyalty and ease of use that make carriers want to spend a lot on iPhones. And WWDC is shaping up to be the go-to venue for software and services.