This is pure speculation on my part ... For that size to be made available and executed i.e. about 4% of the total outstanding shares, if I had to guess, I would say that it is that Lacuna Hedge Fund on the sell side continuing to unwind its position, but that there is a new interested party in the wings. Assuming the buy side buyer is creating an initial position, he/she will have to file a 13-D if they buy 350,000 more shares.
That was right after the Zack upgrade. Apparently that created a buying frenzy. Stock went up to $1.37 soon after. The company has some very important customers now : Microsoft, Oracle, etc. Somebody in the know made that trade. Anyway whoever bought at $.91 has no intention to loose money. That's 36 cents below the current price. For any trader, 65 cents is a great entry point.