Currently, strikethrough is not supported in Markdown README files, or in wiki pages. This is for the obvious reason that the Markdown Syntax doesn't support strike through. (Personally, it's an annoying oversight.) Generally speaking, it's useful to be able to have a todo list, and "cross off" items as you work on them.
In other markdown enabled sites, <del> or <s> can be used. That's not possible, given Bitbucket's policy.
What I propose is extending Markdown's syntax slightly:
- Some Item
- Some Other Item
- ~Some Finished Item~
~ as the character to represent strike through is used in other syntax, and I think would make a decent amount of sense. Since Bitbucket is built ontop of django, it should be possible to implement this as a template filter in a fairly straightforward manner. (I might even be able to submit an example one once work dies down a bit.)
It may seem like a small issue, but I've run into it enough that I felt it's worth devoting a ticket and some time towards. Let's hope the devs agree.