Why this group?

For several months now, my company, http://linnovate.net (known internationally as Drupal.fm), is putting efforts in Drupal based products.
These products are using Drupal as an infrastructure for different kinds of products:
- Pre Customized Drupal sites, destined for publics with similar needs (this is what installation profiles is all about more or less).
This allows customers to save lots of money, because there are no huge building and development costs, but still to have a first class website at their command.
- Web based application. Here we really use Drupal as a tool, and not as a website framework. We tailor an application with the customer, and it is then available through the web, as a service (we host the service)
- Portable web based application. Same as above, only here the service is being packed and sold as a package to the customer, who host the service himself.

While developing these products, we encounter various challenges, mostly framework related, and we discover many advantages and disadvantages of Drupal, in regards to templating a project, so it can become a maintainable product/service.
Recently we all heard about the establishing of Acquia, which seems to be doing just this kind of development.

This group is aimed at service providers who are encountering the same issues as we do, so we can all benefit from each other's experience. It can be a great stage for exposing our projects and products.

Kehilali.co.il (cute way of saying "I have a community" in hebrew) which is "a site for a small village". Small villages may need a website where they can have a bulletin board, discussions and news, they can advertise local businesses etc.... On the other hand - small villages won't usually have the budget to finance building an incredible site using Drupal (we all know this can sum up to few Ks easily). So, we've came up with a configuration that is suitable for 80% of these small villages' needs, and we let them use it for a small monthly fee (that is - we WILL... we're still in the free Beta...)
Now - all the sites share the same themes from sites/all/themes (you should have guessed by now that it is a multisite env!). But - how do you let each site, each village, to customize its CSS (e.g., change the header image, colors etc.) without braking the other sites' CSS? -->