So, the Forsworn Conspiracy is completed in my case but if I visit the Shrine of Talos, even after I've been pardoned the guards there try to arrest me again. Has this happened to others? Think it'll be fixed in the next patch?

Never happened to me. Anytime i see a bug like this i reload the game just before it happened and try again, if it persists every time then its most likely a bug in the game, but most of the time so far for me reloading has cleared up any of these odd issues.

A friend of mine told me that this happened to him as well (which is why I killed the guards), so I think it's a known bug.

Very common and unavoidable bug. It'll probably pat he'd if/when they release a big quest fix update.

It's definitely a bug and almost unavoidable when you do the quest. Kinda pushing that quest off until the next patch comes out that fixes the issue.