Nike received a patent this week on a new new baseball glove with the "air" technology made famous by its shoes. The patent (8,220,071) describes a glove with an L-shaped insert (170), which Nike calls the "palmar force attentuation system."
The insert can be filled with air, foam, or even sulfur hexafluoride, a gas so dense that you can float a boat on it (also, it tends not to leak).
The insert is specially shaped to "enhance flexibility and tactile sensation" while it protects against the "discomfort associated with impacts with balls."
Designed for pitchers, catchers, etc.