Apollo From Adobe

Adobe has released a new cross-operating system runtime called Apollo which allows developers to leverage their existing web development skills (Flash, Flex, HTML, JavaScript, Ajax) to build and deploy rich Internet applications (RIAs) to the desktop. Here's some snippet from the original site:

Apollo enables developers to create applications that combine the benefits of web applications – network and user connectivity, rich media content, ease of development, and broad reach – with the strengths of desktop applications – application interactions, local resource access, personal settings, powerful functionality, and rich interactive experiences.

All you need is download the Apollo RunTime + SDK, and Flex (optional, only if you are interested in) and if you are having some problems, you can always look for technical articles, developer videos, and sample applications. Adobe has also provide some discussion room.