" certain blogs"?
Well that's as clear as mud then.
Is there any guidance as to what is and isn't allowed?
It's not that complicated, honest. Just common sense.
You are perfectly allowed to link to another site provided it is relevant to the subject being discussed. For example, you can link to the dev-team blog, it's the official home redsn0w and pwnage after all.
What we don't allow is promotion of other sites just to drive traffic that way (and away from us), and also we don't allow blogs / forums which support or promote piracy. We also frown on links out of the site if the same or similar content exists here. E.g. don't go linking to a redsn0w jailbreak tutorial on another site.
So provided it is reasonable, you won't fall foul of linking to other sites. If it's not reasonable, we'll soon let you know. Clearer?
Anyway, welcome to the forums. Good to have you here.