COCOMO II is tuned to modern software life cycles. The original COCOMO model has been very successful, but it doesn't apply to newer software development practices as well as it does to traditional practices. COCOMO II targets modern software projects, and will continue to evolve over the next few years.
COCOMO II is really three different models:
Suitable for projects built with modern GUI-builder tools. Based on new Object Points.
You can use this model to get rough estimates of a project's cost and duration before you've determined it's entire architecture. It uses a small set of new Cost Drivers, and new estimating equations. Based on Unadjusted Function Points or KSLOC.
This is the most detailed COCOMO II model. You'll use it after you've developed your project's overall architecture. It has new cost drivers, new line counting rules, and new equations.
Dr. Barry Boehm and his students are developing COCOMO II at USC. We support COCOMO II in SystemStar.