Microsoft has explained their mysterious http://www.microsoft-sony.com domain name by saying that they're great partners with Sony, and that's all there is to it.
"re: sony/ms domain names: Sony = great MS partner. No scoop here, this was just a defensive domain hold. Let's move on to weekend, kay? :)," stated Frank X. Shaw, the lead for corporate communications at Microsoft.
In other words, this domain is absolutely nothing to do with the console industry, and instead is more about other departments within the companies.