There is a way to do intarsia in the round for patterns where both colors are carried through. I posted on it somewhere around here a while back but I'll try to explain it.
When you knit around the first time with the two colors, no problem, right? Kind of like a fair isle. The problem comes when you come around again and you cc yarn is at the wrong end of your pattern. At this point, you knit the background colors and slip the cc, knitting a few more bc beyond the pattern and trapping the cc. Then you turn you work so you're working the purl side. At this point you purl the cc and slip the bc. When you get to the end of the design, you slip the whole thing back onto the left hand needle, turn, and continue on your way. So every other round requires you to slip and purl back.