For the second time in two weeks, a would-be Kindle challenger warns eager buyers that they may not get the e-book readers they’ve ordered in time for Christmas. This time it’s Sony, last week it was Barnes & Noble. Those who ordered the first generation Kindle in the fall of 2007 might recall that Amazon had a similar problem. What’s going on? All three companies source their readers from the same vendor: Prime View International of Taiwan, which also controls the patents for the e-ink electronic paper displays that make e-book readers possible. With more e-book readers to be introduced next year, is it time for someone to pump some capital into PVI so it can expand?