[thetermsheet]

From a purely legal perspective: it's unlikely you're allowed to use logos without permission. From a practical perspective: lawsuits don't usually happen right away and out of nowhere, especially against an open source project! If you use a company's logo, the worst case scenario would probably be them asking you to remove their logo. You remove the logo and everybody moves on...

That said, I am not a lawyer and just providing my opinion based on personal experience.