Hydrogen peroxide powered rocket packs fly for around 30 seconds, because they have a specific impulse of around 125, meaning that one pound of propellant can make 125 pound-seconds of thrust, meaning that it takes about two pounds of propellant for every second you are in the air. Mass ratios are low for anything strapped to a human, so the exponential nature of the rocket equation can be safely ignored.

A pretty hot (both literally and figuratively) bipropellant rocket could manage about twice the specific impulse, and you could carry somewhat heavier tanks, but two minutes of flight on a rocket pack is probably about the upper limit with conventional propellants.

However, an actual jet pack that used atmospheric oxygen could have an Isp ten times higher, allowing theoretical flights of fifteen minutes or so. Here, it really is a matter of technical development, since jet engines have thrust to weight ratios too low to make it practical. There is movement on this technical front, but it will still take a while.

John Carmack

• If we're not coming up with something new and innovative we're stuck making outlook clones. People don't like writing software like that.

What are you talking about?? Writing clones of commercial software is the prime directive of open source! I'm going to go out on a limb and say that actually there are quite a lot of people who like nothing more than doing exactly that.

The above comments about option-<key> works. Also, if you would like to change the keyboard layout, you can do that by going to System Preferences->International and select the Input Menu tab. Here you can select from US, US Extended, Unicode Hex Input, Dvorak, Dvorak - QWERTY command and all kinds of other international keyboard layouts. This is under 10.2.6, I think pre 10.2 the tab menu is called Keyboard.

After selecting the ones you want, a little flag should show up on the menubar which allows easy switching from one input mode to another.