You can create your own permission level in v3 as well. Define custom
<technet.microsoft.com/.../cc287808.aspx> permission
levels

You can't edit  the rights  of a user or group  directly in SharePoint 2007 the way
you could in 2003. Instead you would need to create a custom permission level
with the rights and apply it to the group instead of contribute. To create a
permission level go to site  Actions > Site Settings > Advanced Permissions >
Settings > Permission Levels > Contribute. This will put you in the definition
of the Contribute permission level. At the bottom of the page is a Copy
Permission Level button that will allow you to make a copy and then remove
Delete. Assign the new permission level to the group instead of Contribute.