Yes and No. No, in the fact that currently completely separate events must be registered for in separate transactions. Yes, in the fact that in many cases, you can use our custom fields to setup one event, then give various seminar / workshop / etc options as part of the main event... giving one transaction and accomplishing the same task... actually in a better user experience.
Utilizing the custom fields approach works for most situations, but not all. Just depends on what you're doing I suppose. However, our 2.7 release (coming in about a month) does allow for multiple separate events in one transaction. Thanks.