Google seems to be steam rolling the mobile computing space with mobile apps roll out. They have recently released an HTML version of Google Notebook optimized for mobile phones.
Google Notebook is one of my favorite apps and it was great to hear about this. Access your notebooks on your iPhone by pointing the Safari browser to http://google.com/notebook/m.
In the mobile version, you have a new notebook called "Mobile Notes" where you can add notes directly from the homepage.
However, the current mobile version has its limitations like you cannot edit the notes from the iPhone, even the mobile notes, there is currently no search option, nor can you add labels or change settings.
If these shortcoming are addressed which I would assume Google is already working on; then Google will have another killer iPhone application.