The process isn't so straightforward and seems to mostly be a hypothesis at this point, but the idea has been floated (hehe, good pun!) Icebergs could be wrapped in plastic to keep them from melting and somehow pushed/hauled/coaxed to an appropriate processing area. It's something that companies are looking into further!
Article about icebergs for drinking water: http://www.freedrinkingwater.com/water_quality/quality1/13-08-icebergs-for-drinking-water.htm