Yahoo! Inc. purchased the domain name OMG.com for $80,000 USD on the popular Sedo.com domain aftermarket in early August 2009 and is now putting the domain name to use.
Yahoo currently uses a 301 redirection and simply forwards the domain name (and traffic the omg.com domain already gets: over 26K uniques per month) to it’s OMG site which uses a sub-domain, omg.yahoo.com .
The OMG site on yahoo is a celebrity news and gossip site.
OMG is a popular used acronym for: "Oh My God"
I am not sure why it took Yahoo some 30 + days to do the 301, as the redirection really only takes seconds to do.
Yahoo may have been simply deciding what they really wanted to do with the domain after the purchase. Since brands do not like to go away from their brand, making OMG.com a stand alone site simply owned by Yahoo, might not be what they want to do right now. Yahoo already ranks #1 on most popular search engines for the omg search term using the sub domain.
For the past month since the purchase, by visiting OMG.com would resolve to a dead page. Using a simple 301 redirection will almost always remove any search engine rank placements (SERPs), so it is not the easiest decision or always the smartest to do a 301 redirection if a lot of traffic comes from search engines and the SERP’s the OMG.com domain already had.
What do I think?
I think Yahoo purchased OMG.com because the price was right and they wanted to protect the OMG brand they are creating with the omg.yahoo.com site they have in place. Buying the OMG.com domain prevented "somebody else" from branding the domain, while also likely recovering some traffic they were losing to OMG.com as the general public is not heavily educated on sub domain names .
The 301 redirection is fine. Much better then the dead page for the past month, but I would like to see Yahoo use the domain in some advertising or something just besides the redirection.

