What is GUIMiner-scrypt?
GUIMiner-scrypt is a GUIMiner fork for mining scrypt chains, such as Litecoin.
I want to mine Bitcoin, not Litecoin. Where can I download the original GUIMiner?
Here you can download GUIMiner.
Where can I get news and updates about GUIMiner-scrypt?
Have a look at the official forum thread on BitcoinTalk.