You can't simply log onto iCloud from any Web browser with your Apple ID.

After you update your Mac's OS to 10.7.2, you'll be greeted by this invitation to set up iCloud on the computer.

All you have to do is choose your language, time zone, and optionally change your user picture.

You can sync Mail, contacts, calendars, bookmarks, photos, iWork documents, as well as taking advantage of the Back to My Mac remote control and Find My Mac services.

You get the first 5GB free, and that doesn't count tunes you bought on iTunes.

After you've got an iCloud account set up, here's what the Web sign in looks like.

The iCloud mail service still uses me.com as the domain for email addresses.

Here's what the iCloud start page looks like in a Web browser.

MobileMe users can move some of their services to iCloud, including iDisk, iWeb, and Gallery, but it all goes away next summer. Even now, they can no longer sync Mac Dashboard Widgets, Dock items, Keychains, preferences, and more.

The iCloud mail client is pretty much identical to MobileMe's

The mail app in iCloud always pops open a new window when you compose or reply to an email.

You can choose whether or not to load images, and show message previews, and whether to save sent messages.

You can create up to three email address aliases if you don’t want to give out your real email address.

Shunt emails from certain senders or containing certain text in the subject to specified folders or to the trash box.

The Calendar is beautifully designed to look like a hard-copy calendar. You can add multiple calendars, both private and public, and reminders.

The Contacts app, too, has a book-like feeling. I couldn't import contacts from Facebook or anywhere else in the Web interface, but one can do this on the iOS device.

You can have all your iWork docs synced to iCloud whether you create them on an iOS device or Mac, but you can only download them, not view them from the Web interface.

This feature works nearly identically to how it did in MobileMe.

The maps presented by Find My iPhone give quick, precise results.

This screenshot from an iPhone Settings pages shows what iCloud can sync—though mail isn't showing as I scrolled down to show more items.

When you launch Pages (or any other iWork app) on an iOS device newly updated to iOS 5, you'll see this invitation to use iCloud for sharing documents.