Dell own Equallogic (low-to-mid) and Compellent (mid-to-high).
They already can't quite figure out how to merge the two systems and have been selling both. The inside story is that EQL will go away, but they never seem to go away and Compellent can't quite come up with a product as simple and cheap as EQL. The SC4020, rather than being an EQL with SAS expansion ends up being burdened by Compellent's over-complicated interface system and fiber-channel focused mindset, in addition to being more expensive than EQL (install by a CML certified technician is required, $$$). EQL setup is trivial, I can get one on line in less than an hour.
I think there's also an open question about the mid-long range future of Compellent's primary sales pitch, its automatic tiering of data between different disk speeds (like SSD, 15k and 7.2k) when the future of data storage looks increasingly like it will be all flash, at least for most of the market volume.
What does all that tiering overhead mean in a world dominated by flash? Maybe it makes sense for the absolute largest installs where petabytes are in play, but most of the Compellent installs I've seen have been a shelf of tier 1 and maybe 2 shelves of tier 3. And they're increasingly 10G iSCSI focused, passing on FC.
I can't figure out how they'd blend in EMC to this mix.
What they're probably after is controlling interest in VMware. This would give them a complete vertical play for virtualization, being able to supply compute, networking, storage and hypervisor. They would probably also be in a position to further a lot of network and storage virtualization with control over both sides of the equation, hardware an software.
I do wonder if there's a possible anti-trust question here. I also wonder how Microsoft would feel about it as well.