OS X Lion: Use an SD card
Some Mac computers have a slot where you can insert a Secure Digital (SD) card. You can use an SD card to import images from a digital camera or to store information just as you would with a hard drive.
The SD card slot accepts SD cards and MultiMedia Cards (MMC). It also accepts MiniSD, MicroSD, MiniSDHC, and MicroSDHC cards if you have the appropriate adapter. It doesn’t accept Secure Digital Input Output (SDIO) cards.
If an SD card has been formatted by a digital camera, inserting the card in your Mac performs the same action as connecting the camera to your Mac. For example, if you set iPhoto to open when you connect a camera, iPhoto opens when you insert an SD card formatted by a camera.
Insert an SD card
With the card’s metal contacts facing down and pointing toward the computer, insert the card into the slot.