CustomizeGoogle (CG), the popular and award winning Firefox extension that offers numerous options to customize the search engine (including one option to remove ads from most Google results pages) now has its own blog that's located here.
The most recent blog post mentions that an update to CustomizeGoogle now, "makes it easy to removes[sic] image copying restrictions in Google Book Search (aka Google Print)." The CG home page puts it this way:
Removes image copying restrictions in Google Book Search
This is accomplished by first heading to the "Book" tab in CG and selecting, "Restore Right-Click Context Menu" and then placing your cursor on a page from a book.
I don't believe this feature allows you to print Google Book Search content by just clicking and selecting print. When I tested, I didn't see pages from a book but only the material surrounding the actual page.
However, using the right-click menu (now easily enabled for CustomizedGoogle) and placing a cursor on a page from a book, I was able to quickly isolate the page (as a JPEG file) and then print, save, convert, etc. I was also able to isolate direct urls to book pages and send them via email. You can even save book pages as wallpaper on your PC.
As we've pointed out on this blog before as well as others mentioning it in their writing, content in Google Book Search, particulary new in-copyright content, is not supposed to be printable (short of screen caps).
Of course, limits about how many in-copyright "Sample Pages" you can view are still in place and the "copyrighted material" text is still visible on each page. Google Book Search does offer the full view of public domain materials.
It will be interesting to see how (if at all) Google and participating publishers respond to this new option since it's coming from such a highly lauded software program.
Postscript from the CustomizeGoogle Developer (via Email):
Before, Google disabled right click. With CustomizeGoogle, right click is enabled again, and now you can right click choose save image/view image/etc.
Google also have some restrictions on how many book pages you can view in a single session or per day. If you anonymize your Google ID, you should be able to view more book pages. However, I haven't tested it so I don't really know if it does work.