Now that Sublime Text 1.4 is out in the wild, it's time to look towards the next version. Previously, development has progressed via regular beta releases. There are some grander plans for the next version, which require bigger changes than the beta releases can deliver. Sublime Text X is the solution.
Sublime Text X is a new application built around the same editing core as Sublime Text. Building a new application shell gives the opportunity to make some fundamental improvements to the day to day editing workflow. It will eventually morph into the next stable version of Sublime Text, which will likely be Sublime Text 2.0.
Sublime Text X is currently in alpha status: it works, but it's missing many features compared to Sublime Text, and isn't yet ready to be used for every day text editing. It's available as a preview for registered users: it will be opened to non-registered users at a later date, after it's progressed beyond the alpha stage.
Sublime Text X is cross platform, with downloads available now for Windows, OS X and Linux. Downloads and more information are available on the Sublime Text X page.