Microsoft's successor to the Xbox 360 appears to be called Xbox Infinity, according to a report by The International Business Times.
"Sources have now revealed the console will be named Infinity and that development kits are already in the hands of studios," read the report. This corroborates a recently leaked logo on Reddit. [Update: the logo has been shown to be fake, so we have removed it.]
Elsewhere in the rumour mill, Microsoft remains "uncertain" about its previously rumoured "Xbox TV" video-streaming set top box, according to a report at the Wall Street Journal (via VG247). The report noted that Microsoft is still testing this side-project, and afraid that it might cannibalise its console sales or otherwise not stand out in a competitive market. Last we checked, this Xbox TV project was planned for a launch next year after the new console.
Of course Microsoft still maintains that it "does not comment on rumour and speculation," so we won't know any of this for sure until the new console's unveiling on 21st May.