It just started today it seems. Any ideas?

Because they're awful.

Not down voted ones. I can't see any of them at all.

Something seems broken in the forums, every post I do is eaten... Hopefully this won't either (:P)

When the servers are under strain posts that create a new page in a thread often take a while to show (I'm not sure whether it's a minimum number of posts or an amount of time before the new page actually shows)

Not sure why the servers are under that kind of strain at the moment though as it seems to be particularly widespread right now...

Yep it's not the delay comments I'm having problems with. My comments in some topics are getting eaten. Not in my own topics, but I replied to 1 other topic and it still has not appeared like 2 hours later.

Try temporarily changing the "posts per page" setting and see if that changes anything.

Where exactly?
Check the post count: if you notice a "jump", maybe your post has been downrepped and deleted.

Now all my previous posts appeared at the same time merged in a few posts. I had to edit them because they looked silly... (:P)

Because probably GOG is doing something on the forums, let's hope the outcome will be good...

That thing was happening to me on the first day of the last Pinata Sale. At first I thought I click the wrong button and accidentally close my typing. I try to post my comment again, and nothing, again, and still nothing. After about 30 minutes they finally come out, all of them. So if it's still happening to you, I suggest wait for a bit. It will come out eventually (it does in my case).

I have this glitch / feature at least once a week. I don't know why it happens but it is annoying. My posts apear normally after 1 hour.

Woa, mine never lasted that much.. maybe 10 mins at worst.