yes.. it does that now if you only have a 2 button mouse, and want it to emulate a 3 button mouse.
As specified in the Fedora 14 release notes:
3.5.2. Mouse Behavior
The latest version of evdev, version 2.5, changed the default for the middle mouse button emulation code. This change has disabled emulation of the middle mouse button by clicking the left and right mouse buttons.
220.127.116.11. Enabling the middle mouse button emulation
Middle mouse button emulation can be enabled by the addition of a xorg.conf snippet:
Identifier "middle button emulation class"
Option "Emulate3Buttons" "on"
easiest way would be to take that little snippet of code, and save it in /etc/X11/xorg.conf.d/99-mouse-midbuttonemulation.conf
and of course, you will need to restart X for the changes to take effect