Apple has already sold out second generation iPads in the UK after massive demand in its first weekend on sale. Those ordering online now face a wait of up to four weeks, with the US taking priority. Analysts believe Apple shifted a staggering 500,000 units in the US over the weekend of the 11 March. It is thought supply could also be hit by component shortages following the Japanese earthquake, which could push waiting times back even further. Apple sold out of first generation iPads within days as demand exceeded all expectations, with supply shortages lasting months.