From Facebook Developer Wiki

What are the available values for event_type and event_subtype?

Not sure why this wasn't listed here, but check Event Categories. I've updated this article and events.get. Pete (563683308 11:13, 15 April 2009 (PDT))

[edit] Picture and LInk?

Are there parameters to pass Event picture and to post a link in the Event?

Not at this time, but we're aware of the need for these features. Pete (563683308 08:50, 27 April 2009 (PDT))

It has been added in the last push. But it is not clear how we will be able to use it. I'm not familiar with how this pushes are handled so I still don't know when it will be available for use, I tried the testing console and it doesn't seem to be live yet. The parameter names are not clear yet (I am assuming it will be added to the event_info JSON parameter)--1557560908 12:25, 11 June 2009 (PDT)

It was supposed to have gone out with this week's push, which is why it appeared in the Push Changes article this week. But we decided to continue working on improving performance, so it won't be out until after this coming Tuesday's push (June 16). Pete (563683308 14:13, 12 June 2009 (PDT))