The battery had a model number of A1445 and an Apple part number of 616-0641 and was reportedly 3.72 volts, which is roughly 16.7 Watt-Hour of energy on 4490 mAh of charge. This is far less than the 42.5 watt-hours that a full sized iPad uses and far greater than the 5.45 Watt-hours of the iPhone 5 suggesting that this is a mid-size device, and could be for a smaller 7 inch device.
It is unclear at this point whether the battery is genuinely from Apple. However, according to the report, it is consistent with markings seen on other Apple devices in the past and is proportionate in size for a smaller version of the iPad. The battery is still missing a number of its markings, suggesting that it is still under some work and may be added to the iPad Mini internals at a later point in its manufacturing process.
Will you buy an iPad Mini? Are you looking forward to seeing what it looks like?