Description:
After uploading multiple documents to a document library, you find that the documents are all checked-out. In situations such as a document migration where you are uploading several documents at one time you may not want all of the documents uploaded with a checked-out status because its time consuming to go and check-in each one manually.
Solution:
Prior to doing an upload, disable the setting that require documents to be checked out before they can be edited.
How to do this:
1. Document Library > Settings > Document Library Settings > Versioning Settings"Require documents to be checked out before they can be edited?"
Set this to "No" while doing migration
2. Upload the documentsDocument Library > Upload > Upload Multiple Documents
3. If desired, change the setting back to require documents to be checked out before they can be edited. This will force future document edits to require check-out. It is practical to have this set when working with documents one by one. It isn't practical to have it set during file migrations.
For more information:
http://njbblog.blogspot.com/2009/08/sharepoint-30-clarifying-check-out.html