Super, super busy here in Manila, but this was a bit of a gotcha so I thought I'd share:
If you're looking to update a list item with a publishing html field, don't use the text box in Update Item action directly, as it will html encode all the angle brackets in your html and generally not work as you'd probably want it to. Instead, you need use the build string action to build your html and store it into a workflow variable, and refer to it within your Update Item action - that way, your html won't be escaped and you can do beautiful, beautiful dynamic HTML tables.
P.s. Nintex is AWESOME.