Data Robotics, Inc. just released two new Drobo units (and right after I bought myself a cheap-ass little NAS to backup my existing version 1 Drobo too!).
The first is the Drobo Elite (press release) for a pricey $3499 USD. They claim this unit has the fastest throughput of any Drobo unit, and is aimed clearly at the SAN market, and has been tested with VMware and has some better volume management technology. The other tick list items are:
Secondly is the Drobo S (press release) for $799 USD. This gives you what looks like the "normal" drobo unit, but with an extra drive tacked on (total of 5) and you can choose (and change on the fly) if you want single or double disk redundancy (ability to lose one or two drives).
The "S" doesn't look all that bad, but not a huge significant jump over the previous Drobo, with the exception of the eStata interface, which will make things nice and fast for access. I'm not even going to look at the "Elite", but then again, it's not aimed at me as a user.