Bloomberg News has reported that Microsoft is being sued for $90-million over patent infringements involving Halo. The game allegedly violates two patents developed by MPath Interactive, a company that Microsoft met with prior to Halo's release. The patents were purchased by PalTalk Holdings for $200,000.
Without seeing any of the specifics, this sounds like one of those lawsuits that will be settled out of court for a large sum of money. Anyone remember Sony's lengthy battle with Immersion over the Dual Shock controller? This smells like the same thing.