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
Solaris 2.7 Intel 4G
Solaris 2.7 UltraSPARC 512G
On Linux 2.2 you can get bigger tables than 2G by using the LFS patch for the ext2 file system. On Linux 2.4 there exists also patches for ReiserFS to get support for big files.
This means that the table size for MySQL databases is normally limited by the operating system.