SlingPlayer Mobile always seemed like a perfect fit for the iPhone and it's large display. We have been waiting patiently for it to arrive with it looking less and less likely after rumors of AT&T and/or Apple preventing its release. According to Dave Zatz, SlingPlayer for iPhone is real and is should be up and ready for you to buy (iTunes link) starting tomorrow for $29.99. You will not be able to use it with your AT&T 3G network though as the application is limited to WiFi connections only. Engadget has a post detailing why AT&T won't allow SlingPlayer to work over its network.
Dave is responding to people's questions since he has been using the new client on his iPhone for the past month. Sling Media originally stated you would need to upgrade to a newer Slingbox to use this client and that set off a ton of people. Amazingly, they relinquished on this issue and the SlingPlayer Mobile client for the iPhone will work with all Slingbox units. It doesn't look like the current software lets video fill the entire display, which is a bit of a shame.
PC Magazine also has a full review of the software on the iPhone.
While it is great to see this coming to the iPhone, I am not sure how often I would use it on WiFi since I only use WiFi at home (where I will just watch TV on my large HD LCD) or work (where I am working and won't watch TV content). I could see using it in a hotel while traveling, but it seems that using SlingPlayer Mobile on a Windows Mobile or S60 device with TV out connected to a hotel TV may be a better client at this time.
One reason I have gone to using my HAVA Player and S60, Windows Mobile, and Internet Tablet clients is that all of their mobile clients are free and I can't afford to buy several SlingPlayer Mobile clients for all my phones. I understand Hava is also working on an iPhone client, but it has been pretty quiet since a demo was shown back at CES. $29.99 for the application is quite high compared to most all other applications on the App Store and I will be waiting for a Hava client and skipping this version for now since I just don't see the value for WiFi only connections.