I have heard some things, but I'm not supposed to repeat them.
Lately Project releases have been sort of synchronized with Office releases.
You can find some things on the web about Office.
"We will continue the trend of shipping a new version of Office every two to
three years," said Chris Capossela, the corporate VP in charge of
Microsoft's information worker product management group. "That kind of
predictability is very important for our (Software Assurance) annuity
customers."
Microsoft released its Office System 2003 family of products in October
2003.
I see some sources speculating it will be early 2006. The reality is that
the products usually get shipped when they are finished. Sometimes this is
later than planned, Longhorn is an example of this.
Personally, I'm not all that worried about it. In fact, I use Project 2002
and haven't bothered to switch to 2003. In the standard version there is
very little difference.