That feature was already implemented in many wikis by enclosing the "<references />" custom tag within a HTML standard <div> element with CSS; this was generally done using a references template instead of the tag directly.
What does this mean ?: the "references" tag may now generate its own multicolumn layout, and the existing multicolun div container will split it again in columns because column width/gap/rulers as wel as paddings and margins of the container will interact badly...
Howeer what we still expect to see:
* Please remove the top and bottom margins/paddings that are added to bulleted or numbered lists, or definitions lists (typically used for indenting with ":"), or blockquotes, when they occur inside a multicolumn container : this causes columns to not line up correcly. We don't need these top/bottom margins, it's up to the multicolumn container to set them for all columns simultaneously, and not just the top of the first column and bottom of the last column!)