OpenCalais is a webservice by Reuters that takes an article and tags it with words from categories like city, region, product, holiday, etcetera

OpenDover is a webservice created by us from Byelex and Internet Unlimited that takes an article and a set of base tags. The webservice will then tag the article for each base tag that you sent to the service. It will tag the article with the sentiment for each base tag. Based on all the scores in the article it is possible to calculate a sentiment of the article and of each base tag.

So the only relation between opencalais and opendover is that it is a webservice that tags articles (and a little bit the name).