Thanks to LEGOmom for sending me the B&W image of the challenge mat for Mars Base Alpha: Plan B. I was worried that printing out the mat in B&W would wash out some of the areas that were intentionally done in light gray (the areas where the mission models are placed, for example). Apparently those areas are still visible on the white background. I'll definitely be providing future challenge mats in both full-color and B&W PDF options.
Mars Base Gamma is coming together nicely and is still on for an August 2008 release- one of the missions has turned out to be somewhat difficult (but not impossible) and I'm considering replacing it... but I might leave it in for Bonus Points. To those who are running the Mars Base Alpha challenge, would you prefer easier or harder missions as options in future challenges?