multiple columns with categories

I would like to change the layout to incorporate two content columns (plus sidebar), with each content column showing posts with different categories. I’m simply using the twentyeleven theme and would like to add a child theme to make this work.

I think there are two elements here – setting up the two column layout (and here I mean two content columns, not just additional sidebars) and then adding loops for each column to pull in the category entries, but maybe I’m oversimplifying.

This has bound to have been done and don’t want to reinvent the wheel here (especially as my wheel would probably come out sort of squareish), so would be grateful if anyone could point me in the right direction.

If I can get this sorted I’d like then to move on to effectively putting two category ‘panels’ in the right content column (another level of complication ) so if anyone has any thoughts on that as well, that’d be great.

Thanking you all in anticipation,

Jem