A lot of folks are up in arms about the AutoLink in Google's new beta toolbar (which I mentioned here).
For example, go to select a book at Barnes & Noble. With AutoLink on, the ISBN becomes a link... to Amazon. When you mouse over the link, it shows a special icon to indicate that it was added by Google, but otherwise appears to be a normal link on the page. At this point, the toolbar will not “hijack” a link (that is, if it's already a link, they won't repoint it), but certainly B&N and others will not be happy about links pointing to their competitors.
The common rationalization for this seems to be choice - the user has the choice whether to install (and enable) this feature. The problem with that argument is that it seems that the content publishers need protection here, not the content consumers. As the Google Toolbar becomes more ubiquitous, many can unconsciously be following links that the publisher didn't intend - the only indication being the special icon. (What if I click it by hitting tab?)
I wonder if there are potential legal issues here. For example, if the page is copyrighted, are these changes an unauthorized derivative work? Are there other types of problems that could be raised?
Another interesting aspect here is that Google is starting to strain its universal goodwill. As we know, Microsoft couldn't get away with this (see Dare's commentary). If people start to lose trust in Google, what does that mean for the future of the company?
Update: Kevin says there are probably no copyright or trademark issues, but rather unfair business practices. He also links to Denise who wonders exactly what I thought.
Joshua also weighs in. As I mentioned in his comments, though, the scenario he lays out is a bit of a flawed comparison.