I have SharePoint 2007. When the database backups run using SQLCMD, SharePoint sites go into read-only. Users can't add anything to the sites and the buttons are grayed out. On the backend the databases do not get set to read-only. My question is this, is this normal with SharePoint? I have read some forums that say SharePoint does this by default but the information is a little murky.
This is standard practice. You wouldn't want your users trying to submit changes to a database that is being backed up. Also, stop doing backups during production hours. Schedule them for after-hours or something. It's very poor practice to do otherwise.