It depends on what you are using it for. A lot of people use the logo when they talk about Google on their blog, which is fine. But if you are ripping it off and calling it your own or whatever, then it becomes trademark infringement and it's a big no-no. It all comes down to what do you plan on doing with their logo.
Yup, You can use it for an article, Just don't edit it and add some effects and call it your own Good Luck!
Actually that's not the worst thing that could happen. The worst thing that could happen is: Google files a Cease & Desist order with your hosting company and they shut you down instantly. Google then files an Injunction against you for all future uses of their logo and name (which would hurt like hell if you run a webmaster website...not being allowed to even type "Google" on your website would suck). Google's next move is to file a trademark infringement suit against you, which can result in you losing a multi-million dollar lawsuit and/or face prison time (depending on the court and what their lawyers try to do). You lose the lawsuit (it's Google, how the hell could you win in the first place), and get stuck with a $2 million fine. Unable to pay, you file to Bankruptcy which destroys the fine (and your credit for the next 5+ years) Google would be able to do all this if you use their logo, but the chances of them doing it are so small that most people do it anyways To my knowledge, they've never gone this far against somebody and the furthest they've gone is to take the owner of google.fr to court over trademark infringement, but that is a different story.
I ve had google logos on my website for years, never had a problem with that. It's just free advertisement for google, and i don't think they will mind. And Again I could be wrong.