3.1.3 can be JB with custom firmware.. ur set will upgrade to 3.1.3 but without update ur baseband..
but for locked set don't try it.. bcos still not stable.. my friend update it but he hand itchy go install ultrasnow.. at the end baseband update to 5.12 so he have to wait at the end..

yup.. if u not urgent to update just wait for the tools come out.. u can read some news in google regrading iphone latest JB.. i heard that geohot & dev team have discover how to JB the latest bootroom but he not going to give out so soon must wait the major update like 3.3 or 4.0 firmware come out..

bcos basiclly 3.1.3 is to let ppl to make mistake update so they can stop some JB working like update their baseband let them lost their unlock..

so any sifus here... i have an iPhone 3g OS3.1.3 Bootloader 5.9... so how shall i unlock it? is it forever i have no chance to unlock or i have to wait or there are hardware unlock method for me? please help... thx