Just been reading the Search Engine Roundtable blog and Google have updated the Webmaster Guidelines, the guidelines are pretty much the same as they were before but they now explain in detail what the different methods are, here are the parts that I found interesting and useful:
I have always known that they are against these things, but I haven’t always known what they meant by them, in particular doorway pages, I have never really understood what exactly doorway pages are. There are certain instances where I see pages that are stuffed with keywords and links that re-direct and I just know they are doorways, but there are other instances where I have not been too sure, now I clearly understand what they mean by doorway pages. Basically you need to make sure that each page of a site offers useful information, it also says that HTML Sitemaps are O.K. but to set them up in a way that is easy for people to find exactly what they are looking for.
For more information check out the post at original post at Search Engine Roundtable – Google Webmaster Guidelines Updated