Rotating text in Flex is simple enough, but it frustratingly took me a sufficient amount of digging to find the solution. Thus, a quick note on the topic.

<s:RichText breakOpportunity="all" fontSize="36" fontWeight="bold" lineHeight="20" text="text" textRotation="rotate270"/>

Doing this effectively breaks each character into a row and rotates it. The consequence is lineHeight becomes your new kerning. Not a biggie, but you’ll have to play with it a bit based on the fontSize you’re using.