In a nutshell: Mathflowy = MathJax + Workflowy. That is, it renders your fancy LaTeX math right within your beautiful Workflowy lists.
Yes, it's really that simple.
Include inline math by surrounding it with \( and \) (e.g., \(2 + 2 = 5\)).
Include display math by surrounding it with \[ and \] (e.g., \[2 + 2 = 5\]).
This is experimental and may break at any time, but hey, it hasn't erased any of my data yet. :)