Rockstar tweeted the above image today with no context. No teasers or anything. Clearly a marketing strategy that is already paying off. Countless threads have popped up on Reddit and various other content aggregates and the common theory is a sequel to Red Dead Redemption. Due to the faded look of the logo and how well it matches up to the original media of the Red Dead series, it's hard to draw any other conclusions.
At best we can hope for a new Red Dead game, at worst we can hope for a remaster (which hopefully comes with a PC port).
Any ideas or theories of your own? Post em' in the comments, cowpokes.