Down at Apple's Cupertino, Calif., headquarters this morning, CEO Steve Jobs announced something that many iPhone application developers have been waiting a long time for: Multitasking for third-party apps.

"Happy day," said Bryan Trussel, the CEO of Redmond-based Glympse, when I called and told him the news. "We’ve been lighting incense and worshipping at the altar of Apple to get that," he joked.

The issue is particularly important for Glympse because of the way its service works. People can choose to automatically share their real-time location with other people from their phones. But without the ability to run third-party apps in the background, people who used Glympse on the iPhone had to remain in the app -- without exiting to check email, surf the web or anything else -- to continue sharing their location.

"It’s been far and away the number one thing we’ve been hoping for," and the top request from users, Trussel said. Glympse, founded by Trussel and two other Microsoft veterans, had an office pool leading up to the Apple event, with the odds 60-40 against a multitasking announcement. So in that way, the news was a pleasant surprise.

Location features are among the background services that Apple says it will make available to third-party developers. At the same time, Trussel said a lot will depend on the details of the implementation. He was planning to check into the situation as the news emerges, and we'll update this post if he reports any unexpected hurdles.

Multitasking is available on other devices that Glympse makes apps for, with Trussell calling Android and existing Windows Mobile devices the gold standard in that way. Microsoft is expected to limit multitasking in the next version of its mobile platform, Windows Phone 7, due out later this year.

Other useful multitasking functions demonstrated by Apple at the event included the ability to run the Pandora online radio service in the background while doing other things on the phone.

Update: Here's a message Trussel sent me as a follow-up, which I'm posting here with his permission.

We're popping champagne bottles. Looks like two very cool things are coming out that address our largest limitations on the iPhone.

1) Background processing - (and it indeed looks like location is included in those capabilities). Now our users can send a glympse, and still have their location shared while they are doing all the other gazillion things they do on their iPhones. By far our number 1 request from our iPhone users. Up until now, if they switched tasks, they had to relaunch our app (and they wouldn't be updating during that interval).

2) Almost as exciting (maybe more) for our international users, iPhone 4.0 is allowing access to SMS/Texting from applications. This means we can send a glympse as a text message from our application from anywhere int the world. To date, we only had this option in the US. This is our #1 request from our overseas iPhone users. People were actually sending a glympse to themselves in email, copying the link, opening up text messaging and pasting it in. Now, it will be seamless.

So I'm sure there will be some caveats, and gotchas, but at first blush looks like pure goodness, we've been waiting for a long long time, praying, hoping, dreaming, for this announcement. (always end up disappointed each time in the past).

It's been frustrating to have our top user requests be out of our control.

In reality this just brings iPhone up to where Android, and WinMo, and Blackberry are, but hey it's the iPhone.