When I make an API call to http://external.ningapis.com/xn/rest/WIREDDESIGN/1.0/Activity/recen...
latest blog post I get is from 2012-05-23 ("http://wireddesign.ning.com/xn/detail/6496054:BlogPost:3524) even though there are 10 blog posts after this one (Blog post list: http://design.hotwired.com/profiles/blog/list)
I have attached the output of the API call below.
You're requesting latest activity items, so they may include older blog posts that have had recent activity like comments. If you want a list of recent blog posts, you can query them directly:
Is there a similar end point to fetch forum topics?
Give /Topic a try; it's currently unofficial.