Here is a great video that comprehensively describes the architecture of Flex and Apollo and provides some very good implementation examples. This was delivered by James Ward (Technical Evangelist at Adobe) at a Google presentation.
In addition to this you could see some examples at Web Spiders site at https://www.webspiders.com/flex and https://www.webspiders.com/flex/shoppingcart
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Tags: Adobe Flex, Apollo, web development