If users uploaded hundreds of documents by batch and discovered that they all are now "Check out" & so invisible to all other users . There is a way to have all those documents "checked in" at once.
In OOTB SharePoint,
1. It is impossible to make SharePoint check in multiple files at one time in MOSS or WSS.
2. There is no way to discard check out multiple documents in MOSS or WSS.
3. When multiple documents are uploaded to a document library, the status of all documents is checked out, and you must check in them one by one.
SharePoint Multiple checkin can allow to :
1. Check In multiple documents in any document library at one time.
2. Discard multiple checked out documents in any document library at one time.
3. Upload & Check In multiple documents in document library at one time.