Previous SD games have had a fair variety of grenades, and I think the devs have said Soldier will get "area denial" grenades, e.g. tear gas.
Operatives in previous SD games have been able to use smoke grenades, and the fun thing is that smokes aren't in limited supply--they just take charge (in Brink, "ability pips"), which refills over time.
edit: to clarify, Covert Ops in previous SD games have actually had both regular grenades (of which you can only carry a couple) and smoke grenades (which are in unlimited supply but require energy to throw).
