Upgrading and Jail breaking from 3.0.1 to 3.1.2

Well it seems that the IPA file that I have been trying to get on to my iphone requires 3.1+, unfortunately since my last jailbreak I've left the firmware version sitting at 3.0.1.

Now, 3.1.3 has just been released by Apple around the start of this month. But apparently this is nothing special, unless you have had previous issues with it. Also, a proper firmware patch is not available yet. But it looks like a loop hole has been found. Now it's just a matter of time I guess.

Anyway, I'm not getting much luck in getting information on upgrading from 3.0.1 to 3.1.2 in one go, and jail breaking it. There is a lot of information on the net about jail breaking, with many tools, tutorials, and promises. Some of these even contradict one another. So, it feels like I need to filter the fiction from the facts.

If anyone can assist in answering this, please do... need help with this one.