TinyUmbrella now supports 4.3.1 for the relevant devices. Currently only iPhone 4 for verizon does not have 4.3.1 support (as there is no 4.3.1 available for the verizon iphone). Enjoy!
You can find instructions on how to save your SHSH Blobs below. You need to do this to ensure you can downgrade your iDevice to a lower firmware versions in the future.