Before you go whining like an impulsive brat about a reliable OS X feature that you believe has been sorely ripped out of Lion, rest assure that there’s probably a preference setting for it.

In my case, my beloved Opt+arrow move-by-word key bindings were not working after I upgraded to Lion. Turns out the default keyboard shortcuts for Mission Control were conflicting with them. Go to System Preferences » Keyboard » Keyboard Shortcuts and disable or change Mission Control: Move left/right a space.

Sorry about that :P