iFixit

7-hour battery specifications:

Model A1322

10.95V

60Wh

"This battery contains no mercury (Hg)."

When working on all machines that have internal batteries, disconnect the battery first to cut off power to the entire device.

Apple does offer battery replacement service for $129. If you're not near an Apple Store or service provider, you'll be without your machine 3-4 business days.

Although the batteries look similar, they're definitely not interchangeable. The MacBook Pro's battery is too large (and different in shape) to fit into the older MacBook Unibody.