Here is a link to a google/picasa album... can't figure out how to load pics to the message directly.

Here is a link that might be useful: Yellowed Pumpkin Vines

The plant looks healthy (does not appear to be withering or drying out). I am guessing that this is a sport, which can be a naturally occuring mutation in a plant. I have some house plants that did the same sort of thing, all of a sudden started putting out pale leaves. Took it to my local master gardener and they told me it was a sport and all would be well.

But I will tell you that this is my first year growing pumpkins, too, and I could be completely wrong!

Sandi

looks like you have a nutrient problem. there showing signs of a iron def. you need to get a fertilizer that has all your micro nutrients.

Symptoms:
Iron-deficient plants are yellow and stunted, with the symptoms expressed on the young leaves first. Affected leaves have interveinal chlorosis, with the leaf lamina at first appearing to be a "healthy" yellow.

Control:
Conduct soil and/or foliar nutrient analysis to confirm that the problem is nutritional. Follow recommended practices for fertility using a balanced fertilizer. High pH soils often induce iron deficiency by holding iron in an insoluble form. Powdered sulfur applications may be used on limited areas to lower pH. A number of chelated iron compounds are available for spray application.