Screening tools for gross motor function in 3-5 year olds.

I would be interested to know whether there are any screening tools available for gross motor function in 3-5 year olds.

The best standardized assessment that I know of for this group is the Peabody 2. It may be too specific for a screening tool, but it will give you percentiles and an age-equivalent level for stationary, locomotor and object manipulation skills. It officially goes up to 6 years of age.
I find that it's not the greatest at the upper age limits, because it gets into some skills that are not all that functional, but it's not bad.