Fantastic! I'm so happy, with SteerMouse I finally got my many-functions-on-one-mouse-button-configuration that I used in Snow Leopard to work in Lion (was broken with Logitech Control Center (v3.3.0 and v3.4.0) in Lion).

With the hidden thumb button (HTB) on the Logitech M705 mouse I'm now able to activate the following...

- Mission Control (HTB)
- Application windows (cmd + HTB)
- Show Desktop (opt + HTB)
- Show Dashboard (ctrl + opt + cmd + HTB)
- Show Launchpad (opt + cmd + HTB)

...this makes me much less Trackpad dependent in Lion, and I don't have to move my hands from the keyboard or mouse to do what I normally would have to do with the Trackpad. =D

To make this work, you assign a shortcut key (let's use F12 as an example) to your mousebutton of choice in SteerMouse, and then under System Preferences -> Keyboard -> Keyboard Shortcuts you assign F12 to Mission Control, cmd + F12 to Applications windows, opt + F12 to Show Desktop, and so on.

Theoretically you could have as many as 16(!!) functions on the same mouse button by using various combinations of shift, ctrl, opt and cmd.
However, on my system, I've found that Mission Control is a bit buggy with shift and combinations of ctrl with certain MC functions. I believe this is a bug in Lion, as this behaviour is present with Logitech Control Center as well, but works fine/better in Snow Leopard and Exposé and related functions.

I hope this little tip inspires someone else to try something similar!

Cheers!