Bulk Update Meta Tags?
You may use combination of Metatag, Views and Editable Fileds.


Configure node types to use own fields for meta tags like
keywords, description, abstract, etc. and create it. use Field
Permission to restrict access to this fields.
Configure Metatag to    use newly added fields for filling metatags
on Metatag admin page    or node type page. 
Create view with table    display, add    metatag-fields. Choose
formatter "Editable" on    each field    settings. 
Set path for this    view like admin/config/search/metatags/massedit. Save view and now you    can mass    edit
any fields.


Also you can try Editable Views module.