Dropbox using Softlayer's cloud?

I was configuring the firefall to allow my colleagues get thru. But I saw an suspicious connection to a sub-sub-sub-sub domain of Softlayer.com What the heck!

Then I saw it was Dropbox doing that. Geez! Does this mean that Dropbox is using the cloud provided by Softlayer.com ?

This is a smart way to start business.