Currently the number of blogs, twitter posters and websites devoted to just D&D stagger the imagination. And not just 4e. You can find content and comments on every edition and every campaign published. You can even find sites that list other peoples campaigns. I would say half the fun is finding these sites and exploring them. Your favorite search engine will give you page after page of sites, some will be better than others.
I guess the short answer is what are you looking for. General info, how-to, ideas or something else? That will direct your searches.
I have over 60 book marked links that I have limited myself to. They range from discussions to rules interpretations (crunchy bits).
I would start with the following sites as they tend to have a slightly broader view than just D&D.
Critical Hits - All kinds of things to read and think about
Roleplaying Tips - Fantastic resource of lists, content, ideas and just plan good stuff
Kobold Quarterly - good source of information and ideas.
Newbie DM - Looking through the eyes of a DM who hasn't been DM'ing very long and is willing to share those trials with the world.
Robin D Laws - Author and DM who is the authority on many things RPG
Campaign Mastery - ideas on how to run a better game
Osidian Portal - Other peoples campaigns A great resource
I do not know any of these people (I wish I did), but have found them very helpful and insightful in many ways. Most of these sites have links that will take you to other sights that they follow.