I just happened to read the Entrecard Blog today. Here are a few things I noticed.
1. They will not allow ads for gambling, adult websites, etc.
2. They will not charge a credit fee for rejecting ads (they've responded to feedback from the bloggers).
3. They are not requiring all bloggers to put their ad "above the fold." The rule has been changed to "one page down," meaning within one stroke of the page down key.
This is good news for me--my greatest concern was paying credits for rejecting ads. I'll be as flexible as I can with allowing ads, provided they don't go against my conscience.