There have been a few comments about Cabot and Tablet-K, so I figure I may as well throw in my two cents.
There are probably legitimate reasons not to trust Tablet-K. Rabbi Saffra, who runs the organization, has a habit of jumping to certify products that others won't, and he seems to do most of his business hekhshering cheese and seafood.
There is more than one issue involved in determining the kashrut status of cheese (see Star-K on "Kosher Cheesemaking"). Personally, I think the gevinat aku"m issue is a bit silly. I also don't particularly care whether the Cabot farmers (even those who are Jewish) observe Shabbat. (Note the title of my blog!)
The folks at Cabot can probably be trusted when they claim not to be using animal rennet. Their non-animal enzyme is approved by the American Vegetarian Society (see FAQ's) and Terri tells me that a friend who is allergic to animal rennet finds Cabot cheeses very reliable.
Tablet-K does certify cheeses that contain rennet from kosher animals, but this is noted in the certificate, so people who prefer to eat only vegetarian cheeses have the option of doing so.
In this instance, Tablet-K is good enough for me. I don't mean to tell anyone else what to do.