I have done this; found here:
www.simple-talk.com/.../75810.a\
spx

I must say that you are not going to be able to flatten a group  so that they all
get a task. That is a custom  code requirement...

Why would you need to put all the people in a group  if you want to assign  each
one an individual task?

Well, if you didn't need the individual task  assignments, then using a
SharePoint group  allows you to update the roster without actually having
to edit and re-publish the workflow. If you have the workflow  create
tasks for individuals, then that list of individuals have to be detailed
in the workflow. Any time  there is a personnel change would require an
edit and re-publish of the workflow through sharepoint  Designer.

I understand that there are some ways around this if you create  a more
coded workflow using Visual Studio for instance. It depends on how often
your personnel change I would guess...

In this case you could simply create  a list that contains the people involved.
The workflow  could do a lookup to the list and insert the proper the
individuals. If people change, change the list.

You can dynamically pull users  or groups  to SPD workflow. What you need to
do is create  a people column on the list where you are attach the workflow.
Pull the Users dynamically from the column.