In our working with KNIME we rely on the node description of metanodes and the meta-information of workflows for documentation. It'd be very nice if those descriptions would support markdown, as the markup with HTML is somewhat tedious.
Another thing I'd like to see in future versions of KNIME would be the separation of the metanode descriptions from the tooltip displayed on mouseover. If the description becomes longer than a few words, the tooltip takes up an essential amount of screen space, which isn't very nice.