Someone correct me if I'm wrong here, but does Whiptail actually have any unique IP or real Flash technology? I don't think so.
And to the first post, it seems you've forgotten Dell's original business model was never to develop real IP. They were a very good integrator of Intel/Windows technology, and then expanded into selling their own technology (via acquisition) a bit late, but with acquisitions that have in large been positive ROI.
Violin, Kamarino, and Pure are too high end for Dell and don't match the rest of their portfolio. SolidFire is a specific Service Provider play. Nimbus would be their best bet.