Phishing, the way i understand it is this.
A trojan is placed in your pc and a piece of software waits until you visit a URL like Myspace or even your bank.
As soon as you are connected, the software starts taking mutiple screen shots and sending them back to the server, then a keylogger starts storing the ASCII values of the keys you are pressing and hey presto the screen shots aquire your username and a quick conversion of the ACSII values works out your password too. Its very clever and devious however, keeping your system clear of trojans is all you can do and if you suspect you have it, change your passwords or type it wrong at first then backspace, re-enter and click the mouse randomly just so it makes it that much harder to decypher the code :)
Be safe