Eureka! Somehow the getpage add-on did not get re-installed. So a missing getPage snippet was causing [[+articles]] to not evaluate (since [[+articles]] is just a very long [[!getPage? ...]] snippet call).
I too am having the same issue as described above [[+acticles]] returns nothing. I have tried reinstalling getresources and getpage but neither of these make any difference. I don't want to have to do a new install and i am adding a blog to an existing site with is already pretty big and complex. Any ideas?
Fixed the issue - it would appear that Archivist and TagLister were not installed - installed these and now everything works as i would expect!