Hello Teru,
basically all equipment needs grounding. Cisco recommends to use the grounding holes on their equipment to connect a grounding lug. The nice thing is that these lugs are never in the box, according to Cisco 'the grounding lugs are not available from Cisco Systems; any electrical-connector vendor can provide this lug'.
In general, if your equipment is rack mounted, your grounding is actually provided by the rack itself. Just make sure that a metal part of the Cisco equipment is connected to some other metal part of the rack.
If your equipment is not rack mounted, you might actually want to follow the Cisco instructions, here is a link to grounding instructions for the Cat2900 switches (to give you an example):
http://www.cisco.com/en/US/partner/products/hw/switches/ps606/products_installation_guide_chapter09186a00801d57f7.html#63701
Regards,
GP