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Apple's pulled something fresh from the oven.

Apple CEO Tim Cook and other senior executives took to the stage in California Monday at the company's annual Worldwide Developer Conference, where they revealed a new line of MacBook Airs, a fresh look for the software that runs the iPhone, a new streaming music service, and more at the annual event for software developers.

One highlight of the show was a new Mac Pro, a dark bullet of a desktop computer that for all the world resembled Darth Vader's helmet more than the standard beige box. It will be available later this year, the company said.

But first on the agenda was something of a surprise, for the cat-friendly corporation.

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"I'm proud to present Sea Lion," joked Craig Federighi, senior vice president of software engineering. "We don't want to be the first software release in history to be delayed by a lack of cats."

The name, a parody of the company's reliance on cat names such as "Mountain Lion" for its operating system updates, was a joke. The real name would be OS X Mavericks, he said -- but the software was no joke.

The new operating system will support tagging to help you find files more easily. Simply assign one or more tags such as "important" or "movies" to a particular document as you save it. Maverick will also work with multiple monitors, with docks and menus going across the various display screens. TVs connected via Apple's AirPlay can serve as one of those displays. The new system also promises better battery life.

Apple announced new MacBook Airs with better battery life too. The 11-inch model will have nine hours of battery life instead of five, while the 13-inch model will have 12 hours instead of seven. The new MacBook Airs start shipping Monday: The 11-inch one starting at $999 and the 13-inch model starting at $1,099. The Airs are thinner and lighter than traditional laptops.

The new Mac Pro -- that strange, bullet-shaped spectacle -- will be 1/8th the volume of the existing metallic Pro tower, the company said. Phil Schiller, senior vice president of worldwide marketing, called it a Mac "unlike any we've ever made."

“With the latest Xeon processors, dual FirePro GPUs, ECC memory, PCIe-based flash and Thunderbolt 2, all built around a revolutionary thermal core, the next generation Mac Pro is the most radical Mac yet,” Schiller said.

The 9.9-inch tall computer will be assembled in the USA, he added.

Apple also unveiled an update to the iOS software that powers the company's iPhones, iPads and iPod Touches. Cook said it was the biggest change to the system since the iPhone's introduction in 2007.

Apple's design chief, Jonathan Ive, appears in a video showing a unified look that is applied across the system.

Icons in iOS at present have a three-dimensional look that tries to mimic the real-world counterparts of certain apps. For instance, the icon for the Notes app looks like a yellow notepad and the Contacts app is represented by a leather-bound address book. With iOS 7, Apple is favoring simplicity and consistency. Ive says Apple is introducing a new structure to bring order to complexity.

While design modifications could help Apple distinguish its devices from rival phones and tablets, they risk alienating longtime users. However, the audience cheered after seeing a video on the changes.

Cook opened the keynote by talking about the status of Apple's more than 400 retail stores worldwide. He said Apple's newest store is in Berlin, at a century-old building that was one of the city's first theaters. He also touted Apple's online store: the company has 900,000 apps there, including 375,000 specifically designed for the iPad and its larger screen.

The Associated Press contributed to this report.