The United Newark and Houston to Hawaii deal was aimed right at the heart of Continental — both Newark and Houston and Continental hubs, and United was apparently responding to cheap Continental flights to Hawaii out of United hub Los Angeles (although not quite as cheap as this, and from a market where lower prices tend to be common).
Continental has now fired shots in a different direction — USAirways — with dirt cheap Honolulu fares from Philadelphia, Charlotte, and Pittsburgh. So more folks than before may have an interest, although unlike United these Continental flights will be very difficult to upgrade since Continental charges a co-pay in addition to miles for bumping up to the premium cabin.
I just applied for a fee-waived-first-year Continental card with 20000 miles. Invitation came by mail.