is there a calendar component available?

There is no out-of-the-box calendar component available in our software.  The two calendaring facets currently in the Lithium suite of products are:

a) Polls can be set to start and expire via a calendar in our application

b) Blogs can be published via a calendar in our application

However, if you regularly use a 3rd party calendaring application across your digital properties, it may be able to be embedded into a custom component. 

Depending on how heavyily (or lightly) you want it tied to community actions, what workflows it uses, etc - you might want to open a ticket in the Litho-Case system and ask to speak with somebody from the Lithium Professional Services team about this.  Depending on both the requirements and the 3rd party app, perhaps an integration can be done.