1. If she is confirmed, the Supreme Court will contain no Protestants. Six Catholics and three Jews. No atheists, obviously, but no Protestants? I don't know what it means, exactly, though I have some ideas, but it's interesting.
2. One big criticism - Republican standard- of Kagan is that as a New Yorker, she doesn't represent the heartland. As 538 points out, not uniquely but neatly, the heartland often looks very like a shorthand for 'the red states'*:
can anyone who grew up on the sidewalks of New York really understand an American "heartland" characterized by small towns and rural areas? Maybe not, but neither can the 80% of Americans who live in metropolitan areas. And this gets to the mythical nature of "the heartland," many of whose residents have more in common with middle-class New Yorkers than with the sturdy peasant stock of yore. In terms of this meme, it's revealing that Sarah Palin, who hails from Alaska, one of the two least typical American states (the other being Hawai'i) is reflexively considered a classic representative of "the heartland" and of "real Americans." That shows how artificial the construction really is.
* Bonus fact. 'Red' states being Republican and 'Blue' states being Democrat only solidified, colourwise, in television coverage of the 2000 election. It is not a colour system recognised officially by the parties themselves.