Mac OS X does include an ODBC driver, so Access is accessable. But the demand for MS Access on Macs is virtually nil because better solutions are available.
I prefer to run MySQL on Mac OS X. It has many excellent features, tons of support software are available, it's web accessible and it's free. It also runs on Linux and several other platforms. MySQL is used on the FreeRepublic servers for storing information about user accounts and threads.
Oracle, Sybase and FileMaker RDBMS software is also available for Mac OS X.
Macs also includes a simple database system built-in to the AppleWorks applications suite.