A text column can be up to 65,535 bytes.
An utf-8 character can be up to 3 bytes.
So… your actual limit can be 21,844 characters.
See the manual for more info: http://dev.mysql.com/doc/refman/5.1/en/string-type-overview.html
A variable-length string. M represents
the maximum column length in
characters. The range of M is 0 to
65,535. The effective maximum length
of a VARCHAR is subject to the maximum
row size (65,535 bytes, which is
shared among all columns) and the
character set used. For example, utf8
characters can require up to three
bytes per character, so a VARCHAR
column that uses the utf8 character
set can be declared to be a maximum of
21,844 characters.