, it will work yes?
(Did a quick test myself, just wondering if it is also working correctly)
I have used this method to generate addresses so I think it's reasonable. I actually used vanitygen to generate addresses and modified the code to accept my private key. The current version of bitaddress.org actually accepts private keys but I can't say it did when I worked on it. What's nice is the private key vanitygen gives you yields the same address on bitaddress.org as shown by vanitygen. You could use this as a way to double check.
* Has someone extensively tested that these addresses work and are not sent to the operator of that site or some hardware disc location?
You can go offline after downloading the web page but for the super-paranoid you want to be mindful of a couple of possibilities.
Someone could hack bitaddress.org and place their own malicious code there that:
a) generates bad addresses
b) sends them to a server
c) instead generates them all from a seed that is stored by a server.
* Say someone makes a bad script is it possible to create non-valid addresses/key pairs (ie if I transfer money there they get locked
Can I test addresses somehow?
You can test this process by generating an address however you want to and sending 0.01 BTC to it. Then creating a new wallet at blockchain.info and importing the private key into that My Wallet. Finally, send the coins back to a known-good address of yours. If the transactions is confirmed, your process works (barring security concerns).
* Is the script dependable on your OS and java updates, could it fail if run on a clean Ubuntu install?
I ask all of this as I am about to transfer a decent pile of cash to addresses I want to generate offline on a live cd running Ubuntu.
I guess you mean dependent. Every script needs some sort of environment in which to run. PHP can be made pretty well machine independent. Python too. I'm actually looking at trimming down pywallet.py to create a utility that has the minimum amount of code required to generate a new address and private key and print them to the screen.