I just downloaded tiny umbrella for my Mac. I followed the instructions from a youtube video. I plugged my phone in, it says the device is connected. When I clicked save SHSH nothing happened. I tried it both ways, once with the request SHSH from Cydia box checked and also tried it unchecked( under the advance tab). When I went back to the general tab the field for device model shows MD646LL/A - INVALID ( I'm thinking this has something to do with it). Anyways I thought we had to start saving the SHSH files in case we planned on jail breaking in the future. Any advice is greatly appreciated. Thanks.