Yarss. There's 5MHz between channels on 802.11b, and each channel signal is 22MHz - 30MHz wide, depending on whose specs you trust. Simplifying slightly, basically you're limited to channels 1, 6 & 11. It's really a mess. Even trying to squeeze one more station in, so doing something like 1, 4, 7, 11, can cause enough interference to stop things.