We had two large poplars felled and shredded last year, and of course kept the biiiig pile that resulted.
If there are a good number of green leaves in there that got run thru the chipper with the woodier parts, it WILL heat up and it WILL compost fairly quickly.
It will also mold like you can't believe. My pile, which was like 4-5' high and maybe 10' wide and 20' long, developed a very strong mold layer a few inches down after just a day or so. WHOOO-WEEE you did not want to disturb that unless you were wearing a dust mask, there were huge billows of spores that would rise up everywhere! This took several weeks to subside.
After that, you can regard it as mulch for the first season or two; or let it sit, preferably in a big single pile not a thin layer, for nine months or a year until it is reasonable compost. (If there were few green growing leaves in the pile, however, it will take a whole lot longer to compost, although mixing in some soil and a bunch of high-nitrogen amendment, such as manure or very fresh grass clippings, will speed things along).
In a dry climate, you might have to periodically water the pile and cover it with a tarp, but I didn't here.
It makes wonderful compost (from a soil structure standpoint at least - I have no idea what its nutrient analysis would be but I would guess not especially rich). And the fresher stuff makes great mulch too, or can depending on how exactly it was chipped.
Good luck, have fun,
Pat
