SharePoint 2007 provides the out-of-the-box (OOTB) approval workflow, but unfortunately this workflow doesn't work with groups.
In some cases you need a "group approval workflow", and to avoid custom development you can use the limited version of the OOTB Group Approval Workflow (few people actually know about this) (http://office.microsoft.com/en-us/sharepointserver/HA100951581033.aspx?pid=CH101176771033). The "limitation" is in the edition of the SharePoint you have installed in your environment, because Group Approval Workflow is shipped only with Asian version of SharePoint 2007, due to "a strong demand on this due to their local management style"
The question for us is how to get this Workflow for the English version of the SharePoint 2007. The answer is quite simple - install one of the supported language packs (Chinese language pack, for example) and Group Approval feature will appear on your English site.
Great thanks to the GuYuming from MSFT for the clarifying and testing such behavior.