File Extensions - Are they needed?

If I leave off file extensions completely, will Google index it okay

[SofterLogic UK]

If my internal pages are of the form:

[example.foo...]

(Dynamically managed from PHP, headers changed to OK)

Will that affect Google's facility in crawling web pages? So far only the index page, and the one internal page which isn't of that form show up from allinurl:

[TravelMan]

Not in my experience.

I have urls in the style that you describe and have encountered no spidering or indexing issues.