I've been thinking recently about what a fantastic addition this spell would make to the game. I'm not sure how collision detection works though and if having a spell create a solid placeable item would be a pain. The way I see this working is to have two selections upon cast. To place the wall vertically or horizontally. What use would this be you ask?

Here's a blurb about what this spell does:

"Wall of Force
Evocation [Force]
Level: Sor/Wiz 5
Components: V, S, M
Casting Time: 1 standard action
Range: Close (25 ft. + 5 ft./2 levels)
Effect: Wall whose area is up to one 10-ft. square/level
Duration: 1 round /level (D)
Saving Throw: None
Spell Resistance: No

A wall of force spell creates an invisible wall of force. The wall cannot move, it is immune to damage of all kinds, and it is unaffected by most spells, including dispel magic. However, disintegrate immediately destroys it, as does a rod of cancellation, a sphere of annihilation, or a mage’s disjunction spell. Breath weapons and spells cannot pass through the wall in either direction, although dimension door, teleport, and similar effects can bypass the barrier. It blocks ethereal creatures as well as material ones (though ethereal creatures can usually get around the wall by floating under or over it through material floors and ceilings). Gaze attacks can operate through a wall of force.

The caster can form the wall into a flat, vertical plane whose area is up to one 10-foot square per level. The wall must be continuous and unbroken when formed. If its surface is broken by any object or creature, spell fails. "

In DDO you could use this spell to help you avoid traps, To block off a hallway temporarily to delay enemies, To create a temporary bridges across chasms, to box in a filthy rogue. All in all it would be some fantastic utility and add a unique kind of spell to the repertoire of arcane spell castersand I hope that the developers agree.