If you are using Realms Help as your source of rules, then it says the following:
Any equipment worn or carried by an incorporeal creature is also incorporeal as long as it remains in the creature's possession. An object that the creature relinquishes loses its incorporeal quality (and the creature loses the ability to manipulate the object). If an incorporeal creature uses a thrown weapon or a ranged weapon, the projectile becomes corporeal as soon as it is fired and can affect a corporeal target normally (no miss chance).
There is little difference between throwing a thrown weapon, and dropping an item, so the item would become corporeal.
However, the D20 SRD (which is far more official and recognised) makes no mention of items becoming corporeal at all.