Yes, it is possible.
You can setup subdomains sites like this: subdomain1.domain.com, subdomains2.domain.com.
Then, after you setup the network, use a domain mapping plugin to setup a domain name for each of them. subdomain1.domain.com becomes domain1.com, subdomain2.domain.com becomes domain2.com, etc.
There are several domain mapping plugins out there:
- http://premium.wpmudev.org/project/domain-mapping (the one I would recommend, but it is on a paid membership site)
- http://wordpress.org/extend/plugins/wordpress-mu-domain-mapping/ (free one, but I never used it)