Not sure of the change of registrant status for MOZ.com though I'm certain there are a few WebmasterWorld members who might look that info up and advise.
It appears that MOZ.com was a parked domain through ~2009, parking page via GoDaddy. Archive.org has no records post 2009. The updated WhoIs record for MOZ.com (June 2011) and Moz.org (June 2011) suggest something - a rebranding - may be afoot.
Domain ID:D38613813-LROR Domain Name:MOZ.ORG Created On:26-Oct-2000 10:34:54 UTC Expiration Date:26-Oct-2012 11:34:54 UTC
MOZ.com - expires in a decade. MOZ.org expires in a few months. Hmmmm . . Time to add a few more years . . same for SEOMOZ.org . . unless you want to lose the redirects to some squa . . some opportunist :-/
Of course, Rand et al might advise if a rebranding is afoot from SEOMOZ to just plain old MOZ.
Given the rise of "social media", even in ranking, and how other pathways may be showing rising importance in driving traffic that converts, one has to wonder if the days of "being SEO-centric" are on the wane . . and a timely rebranding may be the best move for players that wish to remain relevant . . to the widest reach of potential clients.
Sgt. Kickaxe probably already knows the background history but there are others who may not know, so this is for their benefit.
Moz is a reference to Mozilla. DMOZ (at the time called NewHoo) allied themselves with Netscape/Mozilla and were available at Directory.Mozilla.org [directory.mozilla.org]. DMoz is a reference to that URL. Directory Mozilla = DMOZ. And that's where Moz comes from.
seoMoz has nothing to do with Mozilla (afaik). I think it was just a popular suffix implying trust so they appended it to SEO. Kind of like how DMOZ was initially named NewHoo (a reference to Yahoo). Yahoo forced NewHoo to ditch the "Hoo" suffix.
Is seoMoz entitled to the MOZ suffix or are they infringing on the Mozilla trademark? That's a legal question I don't have the answer to. There are many non-Mozilla sites using the Moz suffix, seoMoz is not alone.