Apple took several steps Monday to make it much easier for consumers to add new purchases and created content on its ever-growing collection of devices.

Admitting that its $99 MobileMe subscription service “wasn’t our finest hour,” Apple CEO Steve Jobs killed the program Monday and replaced it with the new, and 100% free, iCloud,.

The CEO, who is on medical leave, returned to work Monday briefly to address some 5,100 software engineers at its Worldwide Developer Conference, where new software for Apple computers and mobile devices were also previewed. With iCloud, your new music purchases, books, photos and more get added not just to, say, an iPhone, but also to your iPad, iPod Touch and Macintosh computer..

MobileMe originally was set up to automatically sync calendar updates, e-mails and other data. iCloud now does all that, plus offers automatic backups and distributes them automatically to multiple Apple devices. “If you get a new Phone, just type in your Apple ID and password, and everything will be downloaded to the new phone,” said Jobs.

The full iCloud won’t be available until the fall, but Apple released a beta test version of iTunes in the Cloud for users.

Apple also introduced a new iTunes Match feature to put your existing music collection — songs not purchased by Apple — online and available to listen to anywhere. The new $24.99 yearly service doesn’t require uploading. Apple said it will scan and match your library.

The new iCloud syncs calendar, contacts, mail, photos, documents and music. Apple’s move to put its documents in the cloud from iWork puts office productivity in the cloud much like Google does with Google Docs.

In a demo, Apple Vice President Eddy Cue took a picture on an iPhone, and then opened an iPad and iPhoto on a Macbook, where the image arrived within seconds. Up to 1,000 pictures get saved for 30 days, except for on computers, where they will remain until you delete them.

Another milestone with potentially big implications for Microsoft, Sony and Nintendo: Apple announced its Game Center has grabbed 50 million users in its short 9 months since launch.

Additionally, Apple took several steps to bring iPhone- and iPad-like functionality to Lion, the new Macintosh operating system upgrade coming in July for $29.99.

Using gestures on the notebook touch pad, which comes with new Apple laptops, users can swipe pages right and left, and up and down, just like on the iPad and iPhone, and zoom in.

Apple’s iOS software, which runs the iPod Touch, iPhone and iPad, is getting a big face lift. A new release is slated for the fall.

Among the features:

•Push notifications are getting a new look, with a dedicated home on the device, and a small animation to inform you while letting you continue with your work.

•Twitter is integrated into the operating system, making it possible to Tweet directly from devices, without having to open a separate Twitter app.

•The camera opens quicker. The volume button can be used to take pictures, and editing tools will allow for cropping and red-eye reduction.

• New iPhone and iPad users will no longer have to be plug into computers for activation. Now devices are “PC-free,” Apple said software updates will be over the air, instead of computer based.

•Additionally, the “sync” update will now be done via Wi-fi.

At WWDC, Apple said it now has 54 million Mac users worldwide, with 200 million iPhone, iPad and iPod Touch devices sold to date. That includes some 25 million iPads sold since 2010.