I am looking for the current number of URLs indexed... I want to get
some updated information on a research article that stated in 2003
Google reported over 1.6 billion URLs indexed. What is the current
number?

Hi Jen,

The answer to your question can be found on Google's main search/home page, 
[ http://www.Google.com ].  As of 7/5/04 at 2PM EST, it states: "©2004
Google - Searching 4,285,199,774 web pages".  So, in a year, the
number has climbed from 1.6 billion pages to more than 4.2 billion! 
Google is by far the most comprehensive web search available, so it is
fair to say that the pages of other web indexes will also be included
by Google.

Thank you for bringing your question to us!

Regards,
Andrewxmp

thanks!

4.x billion is the number of pages, not the number of URLs. Given
there are multiple pages per URL, I am guessing the real number to be
billions less...I might be misunderstanding the question though...

I think andrewxmp-ga got the answer correct, see this from Google:

"Benefits of a Google Search

1. Your search covers more than 4 billion URLs. 
Google's index, comprised of more than 4 billion URLs,"
://www.google.com/technology/whyuse.html

Best regards

THX1138