Apple - Is fine volume adjustment possible in OS X Lion?

You can do precise volume adjustment with AppleScript, controlled on a scale of 0 thru 100.

set volume output volume 0 --mute
set volume output volume 100 --100%
set volume output volume 27 --27%

You can get the current volume (also 0 thru 100):

set currentVolume to output volume of (get volume settings)

So, you can write a little script to increment the volume by 2% (approximately what one quarter square used to be):

set currentVolume to output volume of (get volume settings)
set volume output volume (currentVolume + 2)

You can make one for decrementing by changing that plus sign to a minus sign:

set currentVolume to output volume of (get volume settings)
set volume output volume (currentVolume - 2)

If you want to get the volume sound like usual, add the following line:

do shell script "afplay /System/Library/LoginPlugins/BezelServices.loginPlugin/Contents/Resources/volume.aiff"

You can save this as a script or app, and bind it to a mouse or keyboard button (if your driver lets you), give it a keyboard shortcut (as a Service or with another app), or put it in your menu bar (with an app like FastScripts).

⌥+⇧+F11 and ⌥+⇧+F12 were restored in 10.7.4.

I don't have a keyboard shortcut or AppleScript for you, but I did notice - and others seem to confirm - that the slider you can use when you click the volume icon in the menu bar moves much more smoothly in Lion than it did in previous versions of OS X. As I recall it used to sort of jump from level to level, sort of like how it did when you pushed the volume buttons on the keyboard. Now it slides easily between increments.