Does replication add a column to each table automatically?

I don't know enough about replication. Someone mentions to me that replication (may be in SQL Server 2000 and/or SQL Server 2005) will add a column something like a rowid to each table. I hope someone can provide me more information about this. Does this apply to all replication methods? Is there anything that I need to concern relating to this new column?
Thanks.

adding new uniqueidentifier column to published table depends upon the replication type u select. Not all replication add new column. Updatable Transactional replication and merge replciation add a new column to publed table
Refer this link for more info
http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=637605&SiteID=1
Madhu

I would add a columns type guid if you don't have one already.
Pedro R. Lopez
http://madurosfritos.blogspot.com