Here is the list for most useful official Google blogs in English with their descriptions:
The Official Google Blog – Insights from Googlers into our products, technology and the Google culture.
AdWords Agency Blog – The latest from Adwords from you and your client.
AdWords Retail Tips – Adwords tips for the retailers
AdSense Blog – A look inside Google AdSense. With newbie, optimization, AdSense features, and more.
Adwords API Blog – The official source of information about the AdWords API from Google.
Adwords Blog – Google’s official blog for news, information, and tips on AdWords.
AJAX Search API Blog – At this Blog Google gives info about how to use the AJAX Search API.
Google Affiliate Network Blog – News, views and product information for Google affiliate network advertisers and publishers.
Analytics Blog – Here you can get the latest news, tips, and resources from the Google Analytics team.
Android Blog – Blog for developers working with Android, An Open Handset Alliance Project.
Base Blog – Get news, tips, and resources straight from the Google Base team.
Blogger Blog – The Official buzz from blogger.
Checkout Blog – The official Checkout Blog with news for sellers using Google Checkout.
Code Featured Projects – Blog about featured projects on Google Code.
Code Updates Blog – Read all about the latest Google Code updates at the Code Blog.
CPG Blog – News and notes from Google’s Consumer Packaged Goods (CPG).
Custom Search Blog – The latest news, updates and tips from the Custom Search Engine team.
Data APIs – Official Google Data APIs blog.
Desktop APIs – Your official source on the Google Desktop APIs.
Docs Blog – News and notes from the Google Docs team at the official Docs Blog.
Enterprise Blog – A blog about enterprise information, search, and the users that live there.
Feedburner Blog – The Official Feedburner blog of burning questions.
Finance Blog – News and views from the Google Finance team.
Gadgets API Blog – Intended for people who use the Google Gadgets API to write gadgets.
Gears API Blog – Keep up to date on Google Gear’s progress with Gears API Blog.
Gmail Blog – News, tips and tricks from Google’s Gmail team and friends.
Grants Blog – We started this Blog as a place to read about the latest Google Grants news and information
Let’s Take it Offline – The latest news form Google’s TV, Print and Audio Ads team
Lat Long Blog – News and notes by the Google Earth and Maps team.
Mac Blog – Macs inside Google. The official Google Mac Blog.
Maps API Blog – Official Google Maps API blog.
Mashup Editor Blog – The official source of information about the Google Mashup Editor.
Mobile Blog – News and views from the Google Mobile team.
News Blog – The official blog from the team at Google News.
Notebook Blog – At the Notebook Blogs you can read news and tips from the Notebook team.
Open Source Blog – Open source at Google with news about Google’s open source projects and programs.
OpenSocial API Blog – OpenSocial provides a set of APIs for social applications across multiple websites.
Orkut Blog – Your official guide to staying beautiful on Orkut.
Orkut Developer Blog – Learn about APIs, changes and events related to the Orkut developer platform.
Google Online Security Blog – The latest news and insights from Google on security and safety on the internet.
Picasa Blog – News, tips and tricks from the Picasa team at Google.
Public Policy Blog – Google’s view on government, policy and politics.
Reader Blog – News, tips and tricks from the Google Reader Team.
Research Blog – Google research blog where Googlers write about their public research.
Security Blog – The latest news and insights from Google on security and safety on the Internet.
SketchUp API Blog – All about the ins and outs of the SketchUp API.
SketchUp Blog – News and notes from the SketchUp folks.
Students Blog – Google news and updates especially for students
Talk About Blog – A blog about voice, IM and open communications with Google Talk.
Testing Blog – If it ain’t broke, you’re not trying hard enough.
Google Traditional Media Ads Blog – News form Google’s TV, Print and Audio Ads team.
Video Blog – Celebrating creative works from the many contributors to the Google Upload Program
Webmaster Central Blog – Official news on crawling and indexing sites for the Google index.
Web Toolkit Blog – About the open source Java software development framework for AJAX applications.
Website Optimizer Blog – The most up-to-date product news, industry insights, and testing strategies.
YouTube API Blog – For developers using the YouTube API.
YouTube Blog – Official YouTube blog for latest features and happenings.
Ohfffffff ! I am tired. Tell me if you encounter with new ones.