IGN is reporting that some retailers will be getting an exclusive 'Steelbook' packaging. In the US, it will be FYE and Suncoast stores. In the UK, it will be an HMV exclusive. There doesn't appear to be any difference in the DVD content - just the packaging. I just hope this doesn't end up like the Transformers DVDs, where different stores each have their own "exclusive" editions.
On a side note, I've seen numerous comments from people here and other places who seem to be under the impression that Paramount will try to double-dip and release a '2-disc special collector's edition' version of Cloverfield later on. AFAIK, this is not true (Maybe these are the same people who think there are two monsters :). Paramount initially released a Zodiac DVD with NO extras, but there were mitigating circumstances, and that is certainly not the case with Cloverfield. Long ago, before there was any solid information about the DVD, some sites listed all kinds of Cloverfield versions that *might* be available, including a deluxe version and an HD-DVD version. The Paramount Home Video website now has Cloverfield listed, and they show only one version. Sweeny Todd, on the other hand, is coming out next week, and has a regular and deluxe version listed. I assume they both will eventually have a Blu-Ray release, but that is a diffferent story.
* Thanks to The Enchanted One from CloverfieldFans.