I have updated to Snow Leopard and I removed mysql by following this post: http://forums.mysql.com/read.php?11,75256,255853#msg-255853
After that I have installed the mysql 64 bit community edition, but using the prefpane MySQL doesn't start.
Using the terminal gives us some more informations, but I don't know how to interpret them:
stefansmac:~ stefan$ cd /usr/local/mysql-5.1.42-osx10.5-x86_64/bin/ stefansmac:bin stefan$ sudo ./mysqld_safe 100105 13:56:35 mysqld_safe Logging to '/usr/local/mysql-5.0.51b-osx10.5-x86//stefansmac.local.err'. 100105 13:56:35 mysqld_safe Starting mysqld daemon with databases from /usr/local/mysql-5.0.51b-osx10.5-x86/ 100105 13:56:35 mysqld_safe mysqld from pid file /usr/local/mysql-5.0.51b-osx10.5-x86//stefansmac.local.pid ended