If you don't own them, then technically, YES. There are some exceptions, such as news and education, but if the image is copyrighted(and all of them are at the time of creation) it is illegal to post in a forum. Is it enforced? Rarely, but it's still illegal.

Also, Dan's PB account was supposed to be private which means the terms do not apply. Even with the terms they have listed there have been successful lawsuits for images being used commercially that originated from a PB account.

Not everything on the web is free <img src="/ubbthreads/images/graemlins/doh.gif" alt="" /> <img src="/ubbthreads/images/graemlins/doh.gif" alt="" /> <img src="/ubbthreads/images/graemlins/paperbag.gif" alt="" /> <img src="/ubbthreads/images/graemlins/grin.gif" alt="" />