What's Up With Isilon Systems?

Big move today in Isilon Systems: shares of the storage systems company have jumped $1.08, or 19.9 percent, to $6.49, on volume of more than 660,000 shares, or more than 4x the daily average. Today’s rise boosts the company’s three-day rally to 33 percent. So, what’s going on here? Well, here’s what I know.