You might want to look at http://www.firstworks.com/sqlrelay.html
SQL Relay is a persistent database connection pooling, proxying and load balancing system for Unix and Linux supporting ODBC, Oracle, MySQL, mSQL, PostgreSQL, Sybase, MS SQL Server, IBM DB2, Interbase, Lago and SQLite with APIs for C, C++, Perl, Perl-DBD, Python, Python-DB, Zope, PHP, Ruby, Ruby-DBD and Java, command line clients, a GUI configuration tool and extensive documentation. The APIs support advanced database operations such as bind variables, multi-row fetches, client side result set caching and suspended transactions. It is ideal for speeding up database-driven web-based applications, accessing databases from unsupported platforms, migrating between databases, distributing access to replicated databases and throttling database access.
Sounds interesting, thought I haven't had time to play with it yet.