If you’ve been living in a cave, “3.3.1″ refers to section 3.3.1 of the iPhone Developer Program License Agreement. Section 3.3.1 for the iPhone 4.0SDK beta reads:

3.3.1 — Applications may only use Documented APIs in the manner prescribed by Apple and must not use or call any private APIs. Applications must be originally written in Objective-C, C, C++, or JavaScript as executed by the iPhone OS WebKit engine, and only code written in C, C++, and Objective-C may compile and directly link against the Documented APIs (e.g., Applications that link to Documented APIs through an intermediary translation or compatibility layer or tool are prohibited).

It’s been about a month since 3.3.1 came out. The most obvious impact of this is on Adobe Flash CS5. Prior to 3.3.1, Adobe has announced that Flash CS5 will include a Flash-to-iPhone compiler. Now, Adobe has cancelled that feature.

Here’s a roundup of how the other iPhone development tool providers have reacted to 3.3.1. Except for funkaster, writer of shinycocos, most of them seem to be optimistic that they’re in the clear.

AnscaMobile (Corona SDK):
http://blog.anscamobile.com/2010/04/corona-and-iphone-os-4-0/

Torque (iTorque):
http://www.torquepowered.com/community/blogs/view/19715

Unity:
http://blogs.unity3d.com/2010/04/10/unity-and-the-iphone-os-4-0/

funkaster (shinycocos):
http://github.com/funkaster/shinycocos/commit/9ebda7fcfc853db266b4b49c01bdbc5fa5a9be42#comments
(see the comments below the git commit)

Rhomobile:
http://rhomobile.com/2010/04/09/iphone-4-0-sdk-rules/

Me? I’ll stick to learning plain XCode, Objective-C, plus the Cocos2d Library.