[I wrote this entry a little while ago, and is aimed at WSS v2]
Another frequently asked question, this time around the backup and restoration of a sharepoint site.
Generally the STSADM approach is the best way to do this, as all aspects of the site (including permissions) are backed up.
However there is an alternative using SMIGRATE, which only backs up the site data, and upon restoration all permissions will be reset to default.
SMIGRATE
To backup a site with smigrate:
Smigrate -w http://portal/sites/oldsite -f c:sharepointbackupsitebackup.fwp
To restore a site with smigrate:
create a new site but do not apply a template i.e. when asked for Team Site, Document Workspace etc… close Internet Explorer
Then run
Smigrate -r -w http://testportal/sites/newsite -f c:sharepointbackupsitebackup.fwp
STSADM
I was also going to write a “how to” for STSADM but this link says it all really 
http://blogs.vertigosoftware.com/ericc/archive/2006/09/06/3557.aspx
Note: SMIGRATE can be found in “Program FilesCommon FilesMicrosoft SharedWeb Server Extensions60Bin ” on the sharepoint server or download from here: http://www.microsoft.com/downloads/details.aspx?FamilyID=3df85705-5635-40db-adbe-e13ab8684a60&displaylang=en
N.B. I must stress that STSADM should be used instead of SMIGRATE if possible in 99.9% of backup senarios.
