There is an opportunity, but also a danger, with the Internet; unlike printed matter you can update it and revise it. So policy, theoretically, can quickly be changed. But printed matter can also disappear, it is much harder to broadcast a leaflet around the world to show an inconsistency. Websites leave impressions and so if you want to and have the right software you can very simply go back to a previous incarnation of a web page and compare it with the new version. John McCain has done just that. In an argument over Obama's fitness to rule there was some contestation about whether Obama claimed the surge strategy in Iraq was working or not. On July 11th he did say just that, by the 14th there was a slightly more complex argument on offer. McCain has posted the two sites side by side (view here, snapshot is below).
This shows the dangers of saying something publicly, and especially on a website, then reversing that decision and trying to undo it. It is these moments when it is far easier to say actually I was wrong, but I suppose the risk is working out which will play worst in the perception of the voters: is it worse to (as McCain claims of Obama) he lied to make a political point; or is it worse to be wrong?