A simple twitter search of “Steam Mac” shows that users have started receiving emails from Steam allowing them access to the closed beta.

I have heard rumours of an NDA not allowing the users of the beta to post images, but it seems a twitter user by the name of za7ch has posted pictures to twitpic. A few can be seen below:

I’m still eagerly awaiting my invite, but it’s looking less likely this will arrive in my inbox.

*UPDATE* za7ch’s TwitPic where the images had been uploaded to now have now disappeared from his feed, I guess someone didn’t read the NDA!