fake Halo 4 beta test invites.
343 Industries' creative director David Ellis was quick to debunk the bogus site, but the URL used in the phishing scam (halo4beta dot net) is still out there, tempting fate with its Halo-oriented name and un-Microsoftness. Who knows what nefarious maleficence the domain could be used for if left in the wild, so Microsoft has filed a complaint with the National Arbitration Forum in order to have the domain name transferred to its ownership.
In situations like this, the company filing the complaint has to be able to prove that the domain in question was registered maliciously in order for the Forum to decide in its favor. Under the circumstances, we feel like global fraud will probably be malicious enough to sway things in Microsoft's favor.