Prerequisites: Dex 15, Int 15, four or more arms, Improved Multiweapon Fighting, Multiattack, Multiweapon Fighting.
Benefit: If you have four or more arms, you can use each pair of arms to perform a distinct standard action. All such actions occur simultaneously. Thus, you could attack with one or two arms while using a magic item, reloading a crossbow, or casting a spell with two other arms.
Source: Savage Species, page 37.