Using another companies trademarked name in advertisements for your company without their permission is legal?

That post doesn't come anywhere close to establishing "probably not illegal." It's not 100% clear, but it sounds like Network Automation just bid on their competitors' product names to make their ad appear in searches for those products. That's aggressive, but like the court said, it's not particularly confusing unless you just genuinely can't tell the difference between the two products.

But actually using their product name in your ad as a link to your product page, the way GoToMeeting seems† to be doing here? That is very different. I think I would mistakenly click that link thinking I was going to MeetingBurner, and I am more ad-savvy than most Internet consumers.

† Note: I'm not actually going to accuse GoToMeeting of any wrongdoing here. Heaven knows I'd want people to wait for more than a TNW story before they indicted me. I'm just talking about the difference between the two instances.

Bidding on a trademark term, and including a trademark term in an ad to represent something that is not there are two distinctly different things.