Currently you can only enter plain text into the text area's in JIRA. You have no way of specifying a piece of text to be bold/italic, preformatted or coloured.

Due to the circumstances we use JIRA in, it would be extreemly useful if we could say that a block is preformated, or should be displayed using a fixed width font (e.g. Courier New for displaying indented XML / code).

Various options are bulliten board style [b]..[/b] tags, or just regular XML parsed and rouge elements (e.g. script / iframe) ripped out. Although even script / iframe elements have their uses! (e.g. sourcing a js file to dynamically show progress of the latest xml output from a webpage).

Im not sure how you could achieve this, perhaps with custom fields where you specify if "tags" (or whatever you term them as), raw html, or just plain text is allowed. Also you could set things like the URI detector to be optionally selectable on free text fields.

To be honest, implementation isnt really my concern - just the ability is.