I really like some of the jailbroken applications like PDANet and Cycorder. When Apple released iPhone 3.0 firmware last week, I thought I was going to wait for a while until the jailbreaking utilities are ready for the new firmware.
It took only a few days for the iPhone Dev team to publish the jailbreaking tools. The new recommended tool is now readsn0w. Note that it works with original iPhone, iPod Touch, iPod Touch 2G and iPhone 3G. It can jailbreak the supported devices, but it can only unlock the original iPhone, not iPhone 3G. If you have a locked iPhone 3G and you need to unlock it for other wireless carrier, you have to wait for a while.
Here is the link to the download page for redsn0w. The steps are really easy. You just need to use iTunes to upgrade firmware of your iPhone. Then, you can use redsn0w to jailbreak it. iClarifiled has tutorials for the procedures if you like to see some screenshots and the locations for the firmware download.
I tried it last Saturday and found the steps easy to follow. The only problem I had is to put the iPhone to DFU mode. You have to follow the instructions precisely. I suggest you read the tutorial several time before you attempt it.
After my iPhone was jailbroken, Cydia crashed several time when I tried it. After several tries, Cydia seemed to behave normally.