GameTap has released a 'commercial' advertising the original Wing Commander's addition to their service. A special video now plays while you're downloading the game (and at other points in the service). The voiceover narration they've come up with is especially cool... and very respectful towards the game!
The stand-alone SNES version of the Secret Missions addon includes a unique intro sequence (Kilrathi talking about the Sivar weapon) and an 'extended' Tiger's Claw takeoff scene (see fourth screenshot) that makes use of some Mode-7 landscaping stuff.
Source: Exact origin unknown. See news update for details.