What replace the F11 Function in intel macs?

If you have an Apple keyboard, press FN+F11 to get the same result, or use System Preferences to remap it to another key.

 

What kind of Mac and keyboard are you using?

If you look in the Keyboard & Mouse preference pane, under the Keyboard tab, you should see a checkbox for "Use all F1, F2, etc. keys as standard function keys." Check that and the function keys will have their old behaviour back.

 

look in the Exposé preferences. it should tell you the default key for "Show Desktop" in you havent changed it.

 

You can see http://forums.macrumors.com/showthread.php?t=449625 for a discussion about this.