The current size of a MySQL 5.1.30 installation is around 420M.
$ du -sh . 426M .
A further breakdown.
$ du -sh * 213M bin 20K COPYING 9.8M docs 8.0K EXCEPTIONS-CLIENT 436K include 12K INSTALL-BINARY 121M lib 504K man 4.0K my.cnf 77M mysql-test 4.0K README 20K scripts 2.3M share 2.9M sql-bench 100K support-files
A means to reduce the footprint by 25% is to delete some unused stuff.
$ rm -rf docs/ mysql-test/ sql-bench/ $ du -sh . 337M .
It’s no big deal, however it certainly does cut down on verbose output in the backup logs removing the mysql-test directory and files.