I don't know anything about Hannah Arendt outside of these books, but her other works have been on my "to read" list for years now.
So, considering all this, I'm not in any way qualified to contribute to ongoing debates about her work along this line, from Ron Rosenbaum at Slate. I do, however, have a couple of issues spurred by this Slate.com article:
First, it astounds me that any Jewish person could be capable of internalizing "the values of the anti-Semitic literature," as Rosenbaum observes. Perhaps it was the case that Arendt did so more out of considerations of class, but it still astounds me.
Second, is there not an element of "banality" to "evil?" To respond to this, I imagine one must hold that there is such a thing as "evil" in the first place. Some people consider evil to be inherent in the universe. My perspective is that evil is a social construct. There's also a question of evil being absolute or relative.
If evil is inherent and absolute, then all evil is imbued with the essence of evilness and
If evil is a social construct and absolute, then one society may gauge the actions of another society as evil, or call the other society's definition of evil "banal" because it doesn't rate very high on the scale of the first society's definition of evil.
If evil is inherent and relative, or if it is a social construct and relative, then we're looking at a spectrum of evil. People can be more or less evil, or engage in acts that could be deemed by society-at-large to exhibit shades of evil. This, in turn, suggests that there would be a variable scale of banality associated with varying shades of evil.
Within the context of my simplified treatment of the topic above, I take issue with Rosenbaum's critique of viewing "evil" in the way Arendt framed it. Arendt asserted that any of us are capable of doing evil just by doing our jobs, and this seems to me a useful lens of interpretation at times.
 There is also much to be said about "evil" being one of those words loaded heavily with all kinds of temporal, moral, and social baggage, a word that many times drives wedges between us more than it helps illuminate anything, because when we use such words without coming to a consensus about what the word means first, we so often end up at odds before we even begin to attempt to communicate.
 Strikeout and words after added June 8, 2010. I'm not sure what I originally intended here, but I don't think it came across as clearly as first thought.
 This sentence added June 8, 2010.