UTF-8 is an encoding used to represent the Unicode Character set. Other encodings can also be used to represent this same character set. So why does MySQL erroneously call UTF-8 a character set, instead of rightfully calling it an encoding? I am aware that some people confuse the two terms, but from a large, respected software project I would not expect such confusion.
Example MySQL usage:
CREATE TABLE names (name VARCHAR(100) CHARACTER SET utf8);
The MySQL documentation includes a detailed discussion of how they use the terms character set and encoding.
http://dev.mysql.com/doc/refman/5.0/en/charset-general.html