I've never had that problem myself, but now that I think about, I can see how it'd be an issue for people who are used to an environment as large as Reddit. What does help in Hubski's favor is that this place is so small you easily run into the frequent posters day in and day out, making learning who is who an easy thing. It's the infrequent posters that pose a bit of an identifying dilemma.
Someone suggested to mk, and I think he is looking into it, the idea of having the ability to privately tag users. I kind of like this idea, as it's not something I've seen done yet.I've been on the site long enough that the veil of impersonality for all the frequent users has melted away and I can actually pin an individual with opinions, thoughts, and feelings on their pen name. If I were new I would have no way to do that.
I know some subreddits utilize a line of flair (which may be entirely customizable) which I think helps a lot to put a person to the name. Another idea to throw in the pot.