Marco.org

The hotel’s Internet service was secretly injecting lines of code into every page he visited, code that could allow it to insert ads into any Web page without the knowledge of the site visitor or the page’s creator.

Not only are these hotels being creepy and pathetic by using such software, but it’s a potentially huge security hole if the code is poorly written or the systems are poorly guarded, both of which are likely on products like this.

Middlemen injecting ads into other people’s websites also isn’t a new idea, and didn’t turn out very well last time.

As John Gruber said, this is one of many good reasons to skip hotel Wi-Fi entirely and use tethering whenever possible.