Google continues to trim down its product line as part of the company’s new “focus”. The Internet giant announced that it is closing down some more of them, and some functionalities of others.

Google Wave. You may have already thought it was dead. The company announced that it would no longer develop for it over a year ago. Starting January 31, however, it will become read-only, and users won’t be able to create new waves any longer. Users will still be able to export individual waves, using PDF export until the service is turned off. Google notes that Apache Wave and Walkaround are still available. These are open source projects that utilize Wave’s technology.

Knol is making a transition. Google’s Urs Hölzle explains, “We launched Knol in 2007 to help improve web content by enabling experts to collaborate on in-depth articles. In order to continue this work, we’ve been working with Solvitor and Crowd Favorite to create Annotum, an open-source scholarly authoring and publishing platform based on WordPress. Knol will work as usual until April 30, 2012, and you can download your knols to a file and/or migrate them to WordPress.com. From May 1 through October 1, 2012, knols will no longer be viewable, but can be downloaded and exported. After that time, Knol content will no longer be accessible.”

WordPress.com’s Ryan Markel writes:

Starting today, those same authors can move their articles and collaborative journals to WordPress—and they have the power to choose whether to move to a self-hosted WordPress installation powered by the freely-available, open-source Annotum themes, or to have their Annotum-powered site hosted for free here on WordPress.com. Knol will slowly shut down over the next year, and we’ve worked closely with Google, Solvitor LLC, and Crowd Favorite to make this transition as simple as possible.

We here at WordPress.com are thrilled to provide an easy, fast way for Knol authors to move to their new homes without the need for configuring their own installation. And WordPress.com users who would like to start new sites powered by the Annotum platform can activate one of the two new Annotum-enabled themes on new blogs and get started right away. It’s yet another way the WordPress platform and WordPress.com are enabling the democratization of publishing and sharing of information with the world.

Google Bookmarks Lists will end on December 19. Bookmarks within the lists will be retained and labeled.

Google Friend Connect is being retired on March 1. Google wants people to use Google+ instead. Makes sense.

Google Gears-based Calendars and Gmail will no longer be supported at the beginning of December, and then later in December, Gears will no longer be available for download.

The Google Search Timeline is going away. “We’re removing this graph of historical results for a query. Users will be able to restrict any search to particular time periods using the refinement tools on the left-hand side of the search page,” says Hölzle.

Finally, Google has closed its efforts on the “Renewable Energy Cheaper than Coal” project. It says other institutions are in a better position than Google to take on the research, but Google has published its results, and continues to invest in renewable energy.