Late July was busy for Apple. In addition to releasing the new Mac OS X Lion OS, the company announced new Thunderbolt displays and introduced updated Mac mini desktops and improved MacBook Air laptops. The Mac mini and MacBook Air refreshes directly impact business users, a constituency helping to fuel both models’ popularity. Just what changed? Here’s the skinny.

Mac mini

Apple boosted the Mac mini’s processing power, improved graphics performance and added a Thunderbolt port to the popular, bring-your-own-keyboard-and-mouse, pint-sized-but-capable computer. The introduction of Intel Core i5 and i7 processors mean Mac minis can be specified with CPU capacity twice that boasted by previous models. Graphic performance benefits from the refresh, too.

The 2.5GHz model includes an AMD Radeon HD GPU with 256MB of GDDR5 RAM. That means businesses can leverage low-cost Mac minis to power more demanding graphics applications than before, as well as render video more quickly and complete typical tasks faster, thanks to the faster Intel CPUs.

Apple’s Thunderbolt push continues with the Mac mini, too. The I/O standard enables up to 20 times faster performance than typical USB 2.0 speeds.

Currently businesses can choose from three Mac mini models. Two-2.3Ghz and 2.5GHz models-are workstations and one-a 2.0GHz version-is a server. The 2.3GHz version comes standard with 2GB of RAM, versus 4GB RAM for the 2.5GHz model, and both feature 500GB base hard drives and Mac OS X Lion. The 2.3GHz CPU costs $599, while the 2.5GHz version runs $799.

The server version costs $999. It includes 4GB of RAM, two 500GB SATA disks and a 2.0GHz Intel Core i7 CPU.

MacBook Air

MacBook Airs received important updates, too. Possibly one of the most underrated features lost in previous models was a backlit keyboard. New MacBook Airs again include the backlight.

Other improvements to Apple’s incredibly thin-and-light laptop include the addition of a Thunderbolt port, faster processors and the new Lion OS. Available with either 11-inch or 13-inch displays, the 64GB 11-inch model runs $999, while a 128GB 13-inch version costs $1,299.

A 128GB 11-inch model is also available for $1,199. That model includes 4GB of RAM, versus just 2GB for the 64GB model. Both 11-inch versions boast Intel HD 3000 GPUs.

A 256GB 13-inch model is also available. Retailing for $1,599, the model includes an Intel Core i5 CPU and 4GB of RAM. As with the 11-inch models, the 13-inch iterations include Intel HD 3000 graphics processors.

Business users requiring an incredibly portable but powerful laptop can opt to increase the 13-inch model MacBook Air’s build to include an Intel Core i7 CPU for just $100. However, no additional RAM nor a larger flash drive can be specified, meaning the base 13-inch version will prove about as capable a MacBook Air as can be currently had for highly mobile users requiring an advanced processing or graphics-capable machine for powering engineering, scientific, video-editing or other intensive tasks.