As many as half a million of Barnes & Noble's Nook readers will reach the US within four months, southeast Asian tips said today. The bookseller has long said it has been "overwhelmed" by demand, but those aware of its supply chain now tell TechCrunch that about 60,000 Nook devices will have shipped in 2009 and about 500,000 total by March. The number is believed well above internal forecasts and is helped by Foxconn being almost immediately ready to step up its manufacturing.