Instead of five columns, how about tabs? It's not like anyone can read more than one column at a time. Just put "Community firehose", "My friends", "Notifications", etc. as tabs at the top, and when you click on one, that column (what is currently a column, that is) pops to the top.

I turned on ostrich mode to stop some of the blinky scrolly doodads (thanks for the tip, peeps!), but you could also put those on a tab which is only seen when you want to look at it.