As AC just mentioned, the services model in SP2010 is completely architected.
As an architect, this has the following really positive ramifications for me -
1. You can now appoint administrators on a per-service basis. You can do so by selecting a given service, and clicking on the "Administrators" button on the ribbon. These users are then given access to Central Administration. However, they can manage the designated service.
2. Services can now be offered to sites on an a-la-carte basis, rather than an all you can eat buffet style. For example, if a site does not need Excel Services, it does not get Excel Services. The administrator can pick and choose which services are made available to which sites.
3. The third interesting scenario is perhaps the most exciting. Farms can share services. In fact, now you can have an entire farm that can scale out, whose job is nothing but to provide services to other farms. This opens up immense scalability options, and also a great deal of flexibility in the overall architecture considering things such as security, availability etc. Now, the cynical of you might think, what SQL Server permissions will I need to give in this cross-farm implementation? The answer is "None". Managed Farm Services communicate through each other via proxies, thus obviating the need for direct SQL permissions to the parent farm's configuration or service databases.