Digitimes sure think so. Here's what they said:
Global e-book reader shipments from manufacturers to vendors in April-May 2010 reached 740,000 units, with Barnes & Noble's nook accounting for 37% and Amazon's Kindle trailing at 16%, according to Digitimes Research.
I'm going to apply a little common sense here.The Kindle is available in over 100 countries, the Nook only in the USA. I do not see how Amazon could possibly have sold half as many Kindles as B&N sold Nooks.Okay, it is remotely possible, but I find it highly improbable.
Digitimes are also reporting that both Amazon and Sony are going to announce new ereaders this summer. I haven't heard anything yet, but this could be true for Sony. They've dropped the price for all 3 current models, and based on past behavior this could mean a new hardware.