(I said iPhone 2 would feature a second attempt to block unlocking.)
I'm not so sure. If that were the case, they would have done something in each of the firmware releases so far, as the deals were more important at the beginning of the iPhones life than they are now that it's established and has a good following and interest. They could scrap these deals and still sell just as many iPhones, probably more as people who are worried about cracking and unlocking will go for it.
You may be right, but currently I disagree, so here's the slightly longer story.
Long term the big threat to the carriers is that wireless internet destroys their voice revenues with VOIP. Apple and iPhone are champing at the bit for that day. Collectively the carriers want to keep the handset guys under control, and they have succeeded very well up to now by making it appear that handsets are free, and the service is expensive, dictating handset specifications and standing between handset makers and users. But Apple will never surrender its end-user relationship to an intermediary. That's why Apple needs a partner in each territory, who gets a competitive advantage, by stealing subscribers from other carriers, that outweighs the acceleration of carrier business towards commodity status. So Apple needs to do two things: block unlocking, and block VOIP over the voice network to keep the carrier is satisfied until it won't matter any more.
Selling large numbers of handsets is not a good enough result for Apple - look at the state of Moto; they can sell handsets, but they can't make a profit from them. Service revenues are the only way forward, and Nokia is scrabbling to put an iTunes store equivalent in place. As Apple adds services to the iPhone package available only through the preferred carrier, locking will gradually become less relevant, but it's still relevant now.
Coming round to the recent "battle" between Apple and hackers over unlocking / jailbreaking iPhone 1. How else were they to battle harden the software? Why leave visible a weak root password like "dottie" if you didn't intend hackers to swarm all over this and find the weaknesses inside? This whole setup has driven iPhone buzz for a year, has seeded iPhone all over the world with no sales or support costs, created iPhone expertise worldwide ready for iPhone 2, and guaranteed every iPhone made can be sold at retail price for the grey market, even as iPhone 2 is imminent.
This time round there is worldwide distribution (70 countries announced and counting). No way will Apple not give it their best shot at keeping unlocking and jailbreaking under control; they need it for at least another year. As compensation, I suspect iPhone 2 will have the usual carrier subsidies to tempt you into the carrier's clutches.