After Jennifer mentioned it, I finally got curious enough to try to fix the bad behaviour that NW exhibited WRT to the "back" button when nothing is loaded via the content iframe (as is the case with this blog). The problem seems to be fixed on Moz based browsers.
The diff is here. Embarassing that it was broken this long, really.
If you're running IE and this site still "breaks" your back button, please let me know. Thanks.