Maybe someone implemented this before, but I made a small extension that hides BlogEntry items (except modified, drafts) from the CMS sitetree and adds the management/creation of it to a seperate BlogHolder tab 'Blog Entries'.

Requires: SS 3+ and Blog module
Extract it to folder 'extension-hidepages' (CSS relies on it)

2 extension classes are attached to 'BlogHolder' and 'BlogEntry' in _config/_config.yml

BlogHolder:
  extensions:
    - CMSHideBlogEntryExtension
BlogEntry:
  extensions:
    - CMSFormatGridFieldTreeTitleExtension

I couldn't figure out how to make the BlogEntry Title searchable in the GridField. Maybe someone can help me with that?

ps. The extension is quiet generic, except from the name of the extra BlogHolder tab and Griedfield, which means that it can be used for other page types as well.

Very useful this! I installed and it works perfect. The sitetree is much more organized now. Thanks!

There was this module too that does the same thing.

https://github.com/micschk/silverstripe-excludechildren

And this one to manage child pages in a gridfield
http://addons.silverstripe.org/add-ons/christopherdarling/silverstripe-gridfieldsitetree

This is superb - thank you very much for posting. Just what I was looking for! :)