One sign that the iPhone development world is starting to mature is that companies are beginning to build the infrastructure necessary for devs to enable push notification and in-app purchasing. Usually these functions require a developer to make a significant investment in server hardware and labor to set up and operate the push and/or purchase servers, as well as to write code to integrate those services into their apps.

I met with Tim Courtney and Chris Grove of KeyLimeTie yesterday at 360iDev in downtown Denver. Their company's new service, iLime, is a scalable solution consisting of highly reliable server infrastructure and a set of iPhone Application Programming Interfaces (APIs) that make it possible for iPhone developers to integrate Apple Push Notification Service (APNS) and in-app purchase easily.

iLime is making it very easy for small, independent developers to test the waters of push notification by making their APIs and server prowess available for free for up to the first 25,000 push messages each month. After that point, the service is charged on a per-push basis on a tiered pricing structure that makes higher volume more attractive. For in-app purchasing, iLime simply charges a flat US$0.05 fee for every content purchase made through their service.

iLime was first announced at iPhone Dev Camp in August. At 360iDev, iLime announced additional features and detailed documentation of the APIs. Courtney also noted that while there are only a handful of apps in the App Store at this time using iLime's services, several hundred iPhone developers have tested and used the services and they expect a significant number of iLime-enabled apps in the near future.

It's great to see KeyLimeTie making the investment in the virtual bricks and mortar that enable push notification and in-app purchasing, so more iPhone devs can take advantage of these iPhone OS features.

About a month ago we reported that the 360iDev conference was going to be held in Denver, Colorado. The event is now underway, and since I happen to live in the area, I'm attending the event that's billed as the premiere iPhone developer conference in the world.

There are certainly a good number of iPhone developers on hand -- Tom Ortega of 360|Conferences, the group that's running the event, mentioned that the registration was at 225 developers, more than attended the last event in San Jose, CA.

The sessions last for the next day and a half, and there are plenty of opportunities for developers to learn, meet, and party. Stay tuned to TUAW for short interviews and more info from 360iDev.

iPhone developers who weren't able to make it to this year's WWDC are in luck -- the 360 | iDev Conference is planned for September 27 - 30, 2009 at the Curtis Hotel in downtown Denver, Colorado.

The conference is being organized by 360 | Conferences, the team that presented the highly successful 360 | iDev conference in San Jose, CA earlier this year. There's a half-day hands-on advanced debugging session planned for Sunday, September 27th, followed by three full days of sessions by notable speakers such as master iPhone developer Bill Dudney, Phil Libin (CEO of Evernote), and David Barnard of AppCubby.

Conference registration is limited to 400 or so individuals, so if you're planning on attending, it's time to get moving. 360 | Conferences provided TUAW with a special code that you can use to get a 20% discount on registration. Just enter the code phrase TUAWiDevDiscount (case-sensitive) when you register for the conference to receive your discount. They've also provide a discount code (TUAWInMoDiscount) for the InsideMobile Conference planned for this upcoming weekend in San Jose.

With the iPhone app world still showing an amazing amount of growth, this may be the perfect time to build or strengthen your iPhone development skills.