klaatu and Ken were discussing the merits on Markdown and the horribleness of the multitude of markdown flavors.

Here's what I do for shownotes: I write on hashify.me.

Markdown on the left, live rendered text on the right so you can easily Ctrl-click links to check them etc. Then I mark the text on the right, right-click and choose "View selection source" (this is on Firefox). It opens a new tab with the source almost correctly marked. I mark it, copy and then paste into the show notes textbox and choose HTML5 as text type.