There are hundreds of sites with tips on news writing. I have not found any comprehensive ones yet though. Each of the sites below have some nugget of good information, and the last one discusses the link between science blogs and reporting in the mainstream print media.

1. Inverted Pyramid: How to Write for Social News & Blogs

2. Freelancing News Articles: How to Write News Articles

3. How to Write a Good News Story or Blog Posting

4. How to Write a Newspaper Article Quickly and Easily!

5. How to Write News Stories

6. How to Write Newspaper Headlines: Part 1: How to Write News Articles

7. How to Write Newspaper Headlines: Part 2: How to Write News Articles

8. News Writing - The Basics of News Writing

9. Science journalism: Supplanting the old media?