For instance, I see many people reacting to the right's dishonest attacks on Obama by saying "that's not true, he didn't really do that. Here are the facts, I'll prove it to you." Progressives are very concerned that the right isn't out there misinforming the rest of the public and go to great lengths to "set the record straight." By contrast, during the Bush years, when liberals criticized the president, the other side would say "Yeah. So what? He did the right thing." They'd stage a symbolic hissy fit every once in a while to prove their moral/patriotic bonafides, usually over a perceived slight from a hippie somewhere, but they really didn't care if the left "understood" what they were doing or if they approved. In fact, they consciously try to offend them.
I'll give you an example. Obama is being criticized as a tax hiker when he is, in fact, a tax cutter. I wrote a long thing about it yesterday, teeing off of Eleanor Clift's long essay on the same subject. Both of us, I suspect for different reasons, felt it necessary to correct the impression that Obama is a tax hiker. I don't think the right would do that. Assuming that they believed, as liberals ostensibly do, that taxation is necessary and that it isn't a crime to ask people to pay for the government services they receive, they'd say "So what? There should be even more of that and he did the right thing." They wouldn't care that he didn't really raise taxes. They seek to validate their own instincts and/or principles above all.
The best real life example is torture. When we accused the Bush administration of torture, and the Bush administration denied it saying "America doesn't torture", the right flat out said "we think torture of all kinds is a-ok, and anyone who disagrees with us is unAmerican. Thank God Bush protected us by torturing people." They just don't care if the left approves of what they do, and they'd rather have them upset over something that didn't happen than set the record straight and validate the left's beliefs in any way.
Judging from the reaction to last night's cheering for the death of the uninsured, that holds up very well today. They truly believe that people who are "irresponsible" should die (assuming, of course, that decent people like themselves could never be considered "irresponsible.") And they are happy to own anything that upsets liberals.
I realize that this is a very broad observation and there are dozens of examples disproving what I just wrote. But I think it's generally descriptive of the two parties. And the implications of it are fairly clear. Conservatives are always offensive and progressives are always defensive. I guess both strategies are capable of winning, but the former is a lot more energizing and fun.