First, I have spoken to no one about this at either company, thus it is very conceivable that I am wrong - but I doubt it.
Undoubtedly the world thinks this is about cloud gateways. It isn't. It's much more "simple" and far more sinister.
It's because of Box, Dropbox, Egnyte, and the other OFS plays (online file sharing). It is, however, a massive glowing endorsement of using cloud gateways. This isn't generic. This is very Sharepoint-specific.
It's because Sharepoint, Microsoft's fastest growing business app ever, is at risk to those guys.
Sharepoint is AWESOME - as long as you have on-site genius expertise able to sit and tweak the system non-stop. It's a very, very heavy touch IT application. Workgroups who want to collaborate can't just set up Sharepoint to accomodate their needs easily.
Sharepoint is to apps what legacy infrastructure is to operations - a provisioning nightmare.
Thus, just as corporate developers are sick of waiting 5 weeks to have kit provisioned for them to use (so they run to Amazon), business functional groups are sick of waiting for their Sharepoint gods to allow them to play. They realized that they could set up a cloud-based collaboration function at Box in 18 seconds, invite their co-conspirators, and off they go.
They get 90% of what they want out of Sharepoint, in seconds. No IT required. No App support needed.
StorSimple was built from the ground up to enable simple cloud service provisioning for MS apps - namely, Sharepoint.
If MS continued to let their big money customers run away to Box, etc. they would soon be losing a zillion bucks. With StorSimple they can say "now you can get the full features of Sharepoint with none of the headaches" - which isn't entirely true but it sure makes it a hell of a lot closer.
It's all about cloud/user provisioning. Light touch. Fast. Easy.
And, assuming I'm correct, I say Bravo. Sharepoint is WAY too big and important for Microsoft to let slip away without a fight.