If the point is to let people vote from home at their leisure, why not just mail everyone an absentee ballot?
Obviously there are security and coercion concerns that are more detrimental to Internet voting's prospects than the class division aspects. And an absentee ballot sounds reasonable, but is not nearly as convenient as online voting (and has more potential for fraud and coercion than online voting).
My main point is that I believe class disparity is a weak argument against online voting. I don't like using postal mail or waiting in line for an hour or more at the ballot box -- does that mean that it's unfair not to let me vote from home or the library? At least in the US, with libraries, cheap DSL, and cell phones, the vast, vast majority of people not currently voting have easier access to the Internet than they do to polling stations on election day. Don't deny most people a benefit because a few people can't enjoy it.
How is that a problem when most public libraries provide free access, and traditional early and on-time voting are still available?