Enhanced Spotlight Menu
Like smart folders, the Spotlight search menu isn't a new feature in Lion, but it has gained a couple of new tricks.
First, you can now drag any document displayed as a search result directly from the Spotlight menu onto the icon of any app (in the Finder or on the Dock) to open it with that app.
The next addition is the ability to search the Mac OS X dictionary, Wikipedia or the Web (via Google) directly from the Spotlight menu. Dictionary results, if there are any matching your search, will immediately be displayed in the Spotlight menu along with other results such as files, folders and the contents of documents. The Web and Wikipedia search options always appear at the bottom of the menu; clicking them will open the results in your Mac's default Web browser.
The third new Spotlight menu trick is arguably the most helpful. As you mouse over each result in the menu, a Quick Look preview displays next to it. The preview allows you to view and scroll through an entire document without leaving the menu -- a really helpful method to review documents or images to see if you've found the one you were looking for.
Quick Look in the Dock
In the same way that you can view Quick Look previews from the Spotlight menu in the menu bar, you can also see previews of documents from the Dock. The Stacks feature, available since Leopard, allows you to place folders in the Dock for easy access to common documents, applications and other files.
In Lion, selecting a folder in the Dock, moving the cursor over the files inside its Stack and tapping the spacebar on your keyboard will generate Quick Look previews like those available in the Spotlight menu.
Of course, it's well known that Quick Look has gotten its own makeover in Lion, with the ability to select an application to open documents that you're previewing.
FileVault has gotten a massive update. In previous releases, it could be used to encrypt a user's home folder. In Lion, FileVault enables whole-disk encryption for your Mac's hard drive or SSD.
Apple took FileVault even further in the 10.7.2 update for Lion. When it's paired with an iCloud account, any unauthorized use of a Guest account on your Mac will automatically result in your Mac reporting its location to Apple's Find My Mac service -- helping you (or, more likely, law enforcement or security personnel) to locate your Mac.
You will also have the option, through the iCloud.com website or the Find My iPhone iOS app, to forcibly lock your Mac remotely and/or wipe the contents of its startup drive remotely.
Although it's not directly part of FileVault, Lion's amped up security includes whole-disk encryption for drives beyond your Mac's boot drive, including external hard drives. There are two caveats to this process. First, the process of enabling encryption requires reformatting a disk or partition, which will erase any current contents. Second, you will not be able to use the encrypted drive as a startup drive.
You can encrypt a disk by selecting it in Disk Utility and using the Erase tab to erase the drive or partition. (If you're partitioning a drive and encrypting multiple partitions, use the Partition tab.) Choose the "Mac OS X Case-sensitive, Journaled, Encrypted" option from the Format menu.
When you click the Erase button, you'll be asked to enter a password. That password will be required when you connect the drive to your (or any other) Mac. Other than that, you can use the drive as you would any other, as the encrypting and decrypting of its contents is performed by Lion in the background.
This is a powerful and useful option for external hard drives, particularly slim models designed for travel, as it maintains data security if a drive is lost or stolen.
New Tricks for Finder and Trash
There are a handful of helpful new tools for working with files in the Finder in Lion, including when you send them to the Trash.
For starters, you can select multiple items (documents, folders, aliases) and use a contextual menu (right-click or double-tap) to create a new folder containing those items.
Next, you now have the option of multiple undo operations when moving files into the Trash for deletion. Previously, you could undo or undelete just the last file placed in the Trash. Now you can undo moving file after file until your Trash is empty, if you'd like.
Along the same lines, Lion introduces a restore option when you select one or more items in the Trash. This contextual menu item will place any items back into their previous location, whether they were added to the Trash today or six months ago. The only limitation is that you won't be able to restore items if the folder that contained them has been deleted, moved, renamed or is otherwise unavailable (such as an external drive or network share that isn't connected).