Gloves on rotating equipment like an angle grinder are not such a good idea under most uses and circumstances...
Safe Work Procedures
Safe work procedures are formal, written instructions which describe how a task is to be performed. These procedures should incorporate appropriate safe work practices, such as prohibiting employees from wearing loose clothing or jewelry and requiring the securing of long hair with nets or caps. Clothing, jewelry, long hair, and even gloves can get entangled in moving machine parts.
Right from OSHA
http://www.osha.gov/Publications/OSHA3170/3170-02R-2007-English.html#Controlling9
http://www.practicalmachinist.com/vb/general/osha-regs-gloves-while-machining-168191/ Discussion on another board about gloves being mandated with rotating equipment