Apple 10.5.1 Released
An update to Mac OSX Leopard was released last night.

Caused me a few problems on my Imac about which I’ve submitted a bug report. Basically the mouse does not affect the interface without the mouse buttons pressed. This means no highlighting of right click menus, no icon change hovering over a link.
The installer also updated the firmware on the Radeon 2600 in this Imac. I was a little apprehensive as a firmware update from Apple wiped out the motherboard on my Macbook Pro several weeks ago. Supposedly it fixes a freezing issue on new Imacs which I admit I’ve never seen.
Edit – ok with no reboot, 4 hours later this has now sorted itself out!