The subtext of some of the calls for the Clintons to release their tax returns was that Hillary's political career was entirely based on Bill being President. While the public certainly had a right to see the Clintons' tax returns, the media has been noticeably less interested in Cindy McCain's financial information. Even if the news of her selling her investments in Sudanese businesses (a year after candidates from both parties did so) sparks renewed scrutiny, the coverage will likely never take the tone that coverage of Hillary took. John Kerry was similarly mocked for having a wealthy spouse in '04, the implication being that he rode to power on her money.
But despite the fact that John McCain's political career was essentially launched by the money and political connections of his wife's family, you aren't likely to see reporters making the same insinuations. In the novelization of McCain '08, presented by the mainstream press, there's no possible way he could be presented as anything but a self-made man.