TechCrunch's Erick Schonfeld notes that Zend's recent layoff of 25 percent of its R&D team could be a prelude to an acquisition. Schonfeld suggests Oracle and Microsoft as potential suitors, but I think Sean Michael Kerner's speculation (IBM) rings true.
Regardless, Zend would be a great prize. I'm not privy to the company's financial information but don't need to be to believe that Zend's position vis-a-vis PHP (the primary "P" in the LAMP stack) makes it a prime target. It's surprising that no one has picked it up by now.
My sources tell me that Oracle was very close to purchasing Zend back in 2006, but that the two sides were far apart on valuation. With open-source software companies going for a premium these days, Zend's price will have only gone up since 2006.
Who do you think is most likely to buy Zend?