With the iPhone 5 and other armv7s devices now appearing, there are compatibility problems with existing (closed-source) 3rd-party frameworks such as Flurry which are built without this newer architecture.
One option is to wait until they release a new build, but I was hoping there might be a compiler flag or something I can use in my Xcode project that would let the linker know not to expect armv7s architecture from this framework, and use the armv7 instead. Does anything like this exist?
It's not possible to load a framework which doesn't include the targeted architecture.
What you could do is only ship a armv7 app until the frameworks are updated. The app will still work on the iPhone 5, just don't use the latest performance optimizations it offers.
Or if you could live without the framework on the new architecture you could weak link it. But then you need to check in your code if it is loaded everywhere you use stuff from the framework.