MySQL Version 3.22 has a 4G limit on table size. With the new MyISAM table type in MySQL Version 3.23, the maximum table size is pushed up to 8 million terabytes (2 ^ 63 bytes).
Note, however, that operating systems have their own file-size limits. Here are some examples:
Operating System File-Size Limit
Linux-Intel 32 bit 2G, 4G or more, depends on Linux version
Linux-Alpha 8T (?)
Solaris 2.5.1 2G (possible 4G with patch)
Solaris 2.6 4G (can be changed with flag)
Solaris 2.7 Intel 4G
Solaris 2.7 UltraSPARC 512G