Skype for the iPhone was released in the App Store today. Unfortunately, it was crashing on startup - it showed the Skype blue logo and then crashed back to the home screen. A quick Google query led me to discover that I'm not alone - this affects many "jailbroken" iPhone users.
UPDATE: To fix this on a jailbroken iPhone, update the package "Mobile Substrate" on Cydia to version 0.9.2803-1 (or higher). After the update Skype works great!