Sling submitted their iPhone app almost a month ago. Rumours suggested it was rejected altogether thanks to AT&T. Sling says they've gotten no word from Apple either way. But it's definitely looking delayed right now.
While it's designed to work over Wi-Fi and 3G—like that rumoured and delicious Hulu app—AppleInsider suggests it might need to be Wi-Fi only to appease AT&T, who fears what it would do to its network. After all, at best its retracted Skype-and-Sling-banning terms of service update was a Freudian slip. [Boy Genius, AppleInsider]