Question: What is the most reliable and up-to-date source for getting world currency exchange rates?

Answer: 
I consider [Reuters](http://www.reuters.com/finance/currencies) to be THE source.
[Here's one](http://www.forexdirectory.net/quotesfx.html) that appears to be real time.

If you're wanting to trade, you'll likely get something better than this with your forex trading account.