TimesSelect, which includes the Times Columnists and OpEd pieces, is free to print subscribers and costs $95 per year for others. There are approximately 220,000 paid TimesSelect subscribers, representing roughly $21 million in annual revenue. It also provides a perceived benefit to print subscribers.
While I don't know if the Times will recoup that revenue simply from serving ads on the OpEd pages, this is clearly the right thing to do. Putting a wall up around Times columnists simply resulted in reducing the influence of the Times editorial page. In addition to limiting access for direct browsers, it also dramatically reduced the "pass-along" potential of Times content. Once the walls are down, I'd expect their editorial columns to often be at the top of the "most emailed" lists and also receive numerous links from bloggers, Facebook pages and more.
Interestingly, the Wall Street Journal had always taken the opposite tack. While the Journal placed a paid wall around its news content, it left its editorial page open for everyone to read. While its not yet clear whether Murdoch will make the entire Journal free of charge (there are many compelling arguments that it will be profitable to do so), you can be sure that he will continue to make the Editorial Page content freely available. Murdoch clearly sees the value of its influence.
As we move towards the 2008 presidential elections, I think that the public will be well-served by having open access to editorials by both the Times and the Journal.