A select number of current Xbox 360 users have received an offer from Microsoft via Xbox Live offering them a $75 credit if they purchase an Xbox One from any retailer. How Microsoft is choosing which customers receive this special offer is unknown as of this writing. The promo appears on users' Xbox 360 dashboards and says that it's only for Microsoft's "very best customers."
The offer is for selected Xbox 360 owners in the United States, Canada, and the UK.
The rebate offer is only good through the end of the July, but the credit earned from buying an Xbox One is good for a year. The credit must be activated by October 15th though.
When asked for more details a Microsoft rep. offered Eurogamer the following brief statement:
"This short-term promotion is offered to select Xbox fans in the US, Canada and the UK. We are always looking for opportunities to bring promotions like this to our customers, but we have nothing further to share at this time."
(screenshot via eurogamer)