Is it possible to embed a content creation form in views header? Suppose I am building a twitter-like site, and allow members to form groups with OG. So I have set up a view to list all the posts in a given group. However, I would like to embed a content creation form in the header (similar to how twitter is at the moment) with group audience set automatically to the group (therefore is not shown as an option in the form). Is there a way to do it without writing code (I haven't been doing drupal module development after D6...)?
It doesn't have to be in the view header. Just place it block above the view and adjust the css so they sit together. 

If you use entity forms and entity form blocks, you can just place a block above the view block (or panel pane).

Rules will allow you to create a new node, set the current OG_context as the new new node's group and then redirect back to the same page or to the new node.