I have searched for flex plugin for Eclipse but in vain.I have made a serach in google adobe....
A freind of mine told me that you can just cut and paste the installation folder of adobe flex builder into the eclipse Galileo folder
I think what you are wanting is the Flash Builder 4 Beta (plugin version). Adobe renamed it from Flex Builder to Flash Builder as of version 4.
It should be posted in the labs at this link
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