I was recently asked to implement a feature on a Drupal site where all nodes of a certain type would redirect to a main listing page if that node had been unpublished. The problem in doing this is that if a post is unpublished then Drupal will issue an access denied response quite early on in the boot process. When the menu item is loaded it goes through an access callback which sees that the post is unpublished and issues an access denied before anything else can happen. So in this situation you can't use things like Rules to redirect users as the rule is never triggered.
DrupalCamp London, now in it's 4th year, was held of the weekend of the 4th, 5th and 6th of March at The University of London campus in London. Myself and a few other developers from Manchester headed down for the weekend to attend. I wasn't able to attend the CXO day on the 4th, but we were all in attendance for the camp event.
When overriding theme functions in Drupal 7 you would normally copy the theme function into the template.php and alter it to suit your needs. This isn't always convenient though, especially if you are trying to abstract functionality into modules and not have code in your theme layer that is reliant on module code. If you add theme override functions to your module files then they won't do anything as Drupal isn't looking for them there and won't pick them up.
Or, how you can render a Drupal page with an entirely different template.
I recently had a requirement where I needed to get Drupal to render a single page of HTML that was entirely separate from the normal page layout of a site. This was actually part of an API callback, but this got me involved in looking at how delivery callbacks work in Drupal 7. It isn't necessary to create a new theme just for the job of rendering a single page with some custom HTML, especially as Drupal has mechanisms to provide this built in.
The city of Sunderland played host to DrupalCamp North, which saw Drupal users and contributors travelling from all over the UK and Europe to attend. The event, which was held from 24th-26th July, was jointly led by the North East, North West and Yorkshire Drupal User Groups and consisted of a three day sprint, a business day, and a two day conference.
There are a few ways in which you can create complex node access systems. Modules like Taxonomy Access Control and Node Access will allow you to restrict node access in different ways, and work very well for setting up taxonomy or role based access control. There are a few edge cases where you need to restrict access to a node based on some arbitrary conditions like the age of the user or the contents of a field. This is where the build in Drupal access control mechanisms come into play.