How Many Wives Did Moses Have?

I've always thought that Moses had only one wife, Zipporah the Midianite.  Exodus 2 tells us about how he met and married her.
Yesterday, a dear friend and fellow church member put the question to me yesterday about Moses having a second wife.
My friend asked me about Moses marrying an Ethiopian.  I admit that the question puzzled me, so I went and did some research.
The verse in question is Numbers 12:1, which states, "Then Miriam and Aaron spoke against Moses because of the Cushite woman whom he had married (for he had married a Cushite woman)."  Nearly all modern translations (NASB, NLT, RSV, HCSB, LB, ESV, etc.) say "Cushite", but the KJV and NKJV both say "Ethiopian".  I can see where that would be confusing.
So, I consulted my Hebrew Bible.  The term used is clearly "Cushite", so why the confusion?  Why did the KJV translators use Ethiopia?  It's because the land formerly known as Cush is now known as Ethiopia.  The translators saw the term "Cushite" and immediately thought about Cush.
However, the term "Cushite" could describe a person from quite a few different groups of people in different areas.  So, let's consider Exodus 2 again, which states that Zipporah was a Midianite.  I find it interesting enough that the area around Midian was also referred to as Cushi.  Now, Miriam and Aaron complaining against Moses because of that Cushite woman makes more sense, at least to me.
Of course, I may be wrong; I don't claim infallibility on this point because it very well could be that Moses married another woman besides Zipporah.  John MacArthur teaches that Zipporah probably died and Moses remarried.  Is it likely based on this one unclear verse?  You decide.  But even if he did marry again, I think it would be highly unlikely that he married a woman from Ethiopia.