I installed Lion on another partition, then migrated the data from Snow Leopard disk to the new Lion system yesterday. Almost everything worked fine, except mysql, php, and mlDonkey did not work, but I fixed these problems.
Restore the scrolling direction of Mouse
uncheck "Move content in the direction of finger movement when scrolling or navigating"
Logitech Control Center
If you use Logitech mouse like me, you need to upgrade the Logitech Control Center application. Only new LCC supports Mission Control.
I use macports to install mysql and other tools. Macports needs Xcode. Lion uses new Xcode 4.1. Xcode 4.1 can be download with appstore, and now it is free.Read more >>