That could be a bit discouraging, but this approach is hardly any different from the regular browser's cache. The "catch" in the Flex RSLs is that they can be downloaded once from site X and then reused by site Y w/o ever loading them from site Y. If you use the local storage ability, then it has its domain policies - you can't access stuff from other sites (and if you somehow can do it, then it will probably get banned some time later as this is not desired).
So, if you can't reuse the libraries loaded by another site, you are pretty much in the same situation as if you were just to serve them yourself hoping they'll end up in the browser's cache. Best. Oleg
