As a UCC pastor-to-be, I feel qualified to contribute my two cents...
This is correct. The UCC is entirely in the Reformed tradition, which gives it a historical link to Calvinism. However, theology has to be weighed with polity. From a theological perspective, yes, the UCC - rather the denoms which formed the UCC - have a historical tradition of being Calvinist.
However ~
The UCC is congregational in polity, meaning that individual congregations are basically run as a democracy. Yes, there are regions and synods... yet, the UCC overall is very diverse, and prides itself on its diversity. So, with a congregational polity, the "church" as a whole only agrees on something if the majority of congregations vote and say they agree on it. Although there are other congregational denoms, the two biggest (which were both formed by many) are the UCC and the UUA.
So, what does this mean regarding theology?
Overall, the UCC affirms the Bible, the central creeds and tenents of the Christian faith. However, when entering specific questions, and specific interpretations, one would have to look into the individual UCC church. In some parts of the country, the UCC may very well be Calvinist in theology. Other congregations may have made a very conscious choice to reject Calvinism. There are traditional UCC churches, there are Evangelical UCC churches, the one I go to is almost charismatic. Sometimes location reveals a lot, but that is not always the case. The UCC I used to attend in Ohio was extremely conservative and Biblicist in thought. If I lived in the Bible Belt, I probably would not find a UCC church that I felt comfortable in. On the other hand, the UCC in New England is so liberal it is partnered with the UUA.
But individual churches make their choices, whether it be California or Alabama. So, there could be a fundie UCC in California, and there could be a flamingly liberal one in Alabama. They also make their own choices whether or not to be ONA (open and affirming) regarding gays and lesbians. In any case, one's ONA status is a reflection of what that congregation believes.
Hope that helps.
Oh, please no. Anyone but Hillary. Seriously. Well, not just anyone, but either McCain or Obama over her. Sorry, I just really do not want to see any more of the Clinton regime.