I have a Captivate and have also pushed the FMRadio.apk to the device.
EVerything runs great - except when one tries to play a station - then an error is received: "Unable to turn on FM Radio"
I have spoken to a dev or two and they are not convinced that the hardware is the same on our devices. It appears from this post:
http://ip208-100-42-21.static.xda-developers.com/showpost.php?p=7057871&postcount=18
Edit: The person who made the above post works for Broadcom so this chip: InCrystal 20751 should be the same as the BroadCom20751. And, it is in (at least) the I9000's.
Anyway, the nomenclature on the I9000 is: SWB-B23 which is just the print on the protective metal cover.
Bottom line: First - we need to definitively know that the same GPS/FM/BT chip is in the US variants as is in the I9000. *Anyone willing to pull apart their device to see what the cover says If it has the same nomenclature then we'll know. Secondly, until we can get the Captivate's (or, Vibrant's for the T-Mobile users) kernel so we can look around inside and modify it (ie: add the drivers from the I9000 kernel) - we probably won't get the radio working. This is because currently everyone is having to use the Captivate/Vibrant specific kernels to have a working phone one their carrier.
Yes, some are using the new froyo release made for the I9000 on the Captivate/Vibrants - however, they are flashing the Captivate/Vibrant kernels on afterwards - that is why they are not seeing the same performance increase as the I9000 counterparts - and, since many of the drivers are included in the KERNEL that is my suspicion as to why they also don't have a working FM Radio.
The only possible solution I have heard of is "cross-flashing" the kernels - whatever that is... Or, trying to find a way to add in the drivers after the device has been flashed and is working...
Wish I knew how to pull apart the binary kernel/boot.img and put it back together. But, it seems Koush made a post on another thread that the Captivate kernel isn't unpacking without corruption. I'll try to find his post and update this later today.