Widescreen layout
A new layout for Mail takes advantage of the widescreen display on your Mac. It neatly arranges your message list and open email side by side in full-height columns, so you see more of your messages.
Full-screen experience
Mail delivers a full-screen experience, so you can read and send email without distractions. With more room for your conversations and messages, you can browse your email more efficiently. Compose a new message, and Mail dims your inbox and slides in a full-height canvas so you can focus on your message and capture your thoughts.
Favorites bar
The favorites bar gives you one-click access to your mail folders. Its horizontal layout displays your favorite folders and their unread counts without cluttering up your window. Drag folders to the favorites bar to add them.
Redesigned message header
The message header displays only the information you need, so you can focus on the message. Click the details to see everything else, including recipients.
Conversations
Conversations in Mail gives you a new and natural way to read and manage your email. As email arrives in your inbox, Mail automatically groups related messages in conversations. And Mail numbers each message in a conversation so you always know where you are as you read.
Custom labels
Organize your mail with color-coded labels. Labeling a message takes just a click, and a colored flag is added to the message for easy identification. Mail creates folders for your labeled messages so you can get to them quickly. You can personalize labels with names like “Family” and “Work.” And you can use labels when you search to help narrow the results.
One-click archive
Quickly move messages from your inbox and save them for later with a single click.
See everything on your Mac
Mission Control brings together everything running on your Mac — open windows, full-screen apps, spaces, and Dashboard — in one bird’s-eye view. A row of thumbnails across the top of the screen represents Dashboard, desktop spaces, and your full-screen apps. The lower part of the screen shows an Exposé view of the open windows on your desktop. Click anything to instantly navigate to it.
Add and remove spaces

You can add and remove desktop spaces right from Mission Control. To add a space, click the new Spaces control (+) in the upper-right corner of Mission Control. Or drag an app or window to the Spaces control. To remove a space, click the Delete button (x) on the space’s thumbnail.
Bind application to a space
You can now bind an application to a particular space or make it available in all spaces right from the Dock. Press and hold the icon in the Dock and make a selection from the contextual menu.
Custom desktop pictures
Each desktop space can have its own desktop picture.
Full-screen Photo Booth
Photo Booth in OS X Lion delivers a full-screen view that takes advantage of the entire screen on your Mac. And it features a new look that makes you feel as if you’re in an actual photo booth.
New effects
Have even more fun with the built-in camera on your Mac. Choose from nine new effects that use facial tracking technology, so effects look great whether you’re front and center or left of center. Effects include Lovestruck, Dizzy, Frog, Nose Twirl, and Blockhead.
High-resolution photos
Photo Booth takes advantage of the high-resolution FaceTime camera in some Mac computers, so you can show off your smile in richer detail than ever before.
Full-screen Safari
Take Safari full screen and experience your favorite websites on a grander scale. It’s perfect for viewing more of your Gmail inbox, Facebook newsfeed, or Twitter trends.
Downloads list
When you download files in Safari, an arrow appears to the right of the Smart Search Field to show you the progress of your download. Click the arrow to see downloads. You can also clear downloads from the list or view them in the Finder.
Drag-and-drop downloads
You can drag downloaded files from the Downloads list to your desktop for easy organization.
Reading List
Reading List lets you save web pages to read when you have time.
Per-user screen sharing
You can remotely log in to a Mac with any user account on that computer and control it, without interrupting someone else who might be using the computer under a different login.
Go full screen
Take the screen-sharing application full screen in Lion so you can observe and control a remote Mac using the entire screen. It feels as if you are sitting right in front of the other Mac.
Records the history of a document
OS X Lion can keep an ongoing record of your document as it evolves. Lion records snapshots of your document as you make changes or reach important milestones.
Automatic versions
Each time you open a document, Lion automatically saves the current version. It also saves a new version every hour while you work, building a history of the document as you go.
Browse versions
Lion makes it easy to browse previous versions. Using an interface similar to that of Time Machine, you can browse the version history of a document to see how it looked at any time. A timeline shows all the versions that exist for the document. To view a previous version, simply click a specific date.
Side-by-side comparison
When you’re browsing versions, a side-by-side comparison feature allows you to see the current state of a document next to the previous one, so you can easily note the differences.
Other Features
Resize from any edge
You can now resize a window from any side or corner.
Overlay scroll bars
The new overlay scroll bars appear when you need them and fade away when you don’t, resulting in a more streamlined experience.
Interact with iTunes artwork in screen saver
Turn your screen saver into a jukebox. Just click an album to play the songs.
And the best part? It's only $29.99 and available from the Mac App Store sometime in July! Can't wait!