"Community Trees are lineage-linked genealogies from specific time periods and geographic localities around the world. The information also includes the supporting sources. Most of the genealogies are joint projects between FamilySearch and others who live locally or have expertise in the area or records used to create the genealogies. Each Community Tree is a searchable database with views of individuals, families, ancestors and descendants, as well as printing options."
Here is the home page:
There is a simple Search box on the home page, and a link to an Advanced Search function. I clicked on Advanced Search and this form opened. I clicked on the list of available databases:
There are only 19 trees on the site at this time. I realized that the British Isles Peerage tree might have some of my ancestors included, so I clicked on that, and then guessed that Olive Welby would be in this database, so I entered her name in the search form:
After scrolling to the bottom, I clicked on Search and was rewarded with one match:
So Olive Welby is included in this tree. I clicked on her name and a Family Group Sheet on the "Individual" tab appeared:
There is a row of tabs at the top of the page - Individual, Ancestors, Descendants, Relationship, Timeline, GEDCOM and Suggest.
The data for each person in the Pedigree Chart can be seen by clicking the down arrow just below the box with the person's name.
That's as far as I've explored so far. There is an option to download a GEDCOM file of up to 12 generations of ancestors and descendants.
NOTE: The Ancestry Insider has a post this morning with more information about the site in FamilySearch Community Trees.