Fantastic Literature stocks Interzone 243.
As does Transreal.
Interzone 224 has now been published and you can read some samples of the contents here. You can also order it directly from there as well, or get it from Central Books, Borders, Transreal, many branches of Forbidden Planet, and lots of other places.
Transreal Fiction in Edinburgh stocks Interzone. They are named after one of Rudy Rucker’s books, and the current issue contains one of his stories.
Think of it as a Mobius strip.