Its not just ibuprofen that can interfere with a fusion, its any NSAID (Non-Steroidal Anti-Inflammatory Drug). Here is a pretty complete list of the drugs in this class for easy reference. If I missed any, I apologize.

Aspirin
Diclofenac Potassium (Cataflam)
Diclofenac Sodium (Voltaren)
Etodolac (Lodine)
Indomethacin (Indocin)
Ketorolac (Toradol)
Sulindac (Clinoril)
Tolmetic (Tolectin)
Meclofenamate
Mefenamic acid (Ponstel)
Fenoprofen (Nalfon)
Flurbiprofen (Ansaid)
Ibuprofen (Motrin, Advil)
Ketoprofen (Orudis, others)
Naproxen Sodium (Anaprox, Aleve)
Naproxen (Naprosyn)
Oxaprozin (Daypro)
Nabumetone (Relafen)
Difusinal (Dolobid)
Salsalate
Celecoxib (Celebrex)
Meloxicam (Mobic)
Piroxicam (Feldene)

In addition to being held for several months after fusion surgery, these drugs are often stopped a week or two before the surgery. I believe to decrease bleeding complications during the surgery more than for the anti-inflammatory effect.