Im a Slate Plus subscriber with a gmail address and I have no trouble accessing the Slate Plus content. I like that its still easy to access a chronological feed on the iPhone app. I have experienced occasional glitches with the chronological feed after becoming a Slate Plus subscriber, but they can be "fixed", by deleting and reinstalling the app. Thats the only reason this is less than 5 stars.
njmoo about Slate.com