...Do you simply unwrap them and expose them to direct sunlight, or do you shield them with shade cloth for several days to let them acclimate?    It looks like I may be wrapping some of my trees next winter.  Any pointers?

Dave...when I winterize my trees I tripple wrap them eg. burlap, weed cloth, and plastic tarp...when I unwrap them, I simply remove all three layers and let nature take it's course...been doing it that way for seven years with no problems.

At the point you unwrap they should have no leaves.  So there would be no reason that I can think of to transition them slowly to sun.  So like Vince I have unwrapped the tree, exposed it to full sun and have had no problems.

Do you guys wait till after the last frost, or just when temps start warming up a bit?

When I think there'll be no more temps under 30, unless it's already sunny & hot during the day then I wait till after the last frost.  I check frequently though, and if leaves are emerging I unwrap it.  It will recover from frost damage better than light starvation.  :)

Dave...in my case I'm not too concerned about a frost because as of yet there are no leaves on the trees...I uncovered all my inground trees last Saturday(March 16th.), and we have had 3 nights with temps in the 30's(last night was 28*)...they are exposed in the day time to 50* temps and will break dormancy in another week or so...by that time temps will be milder(40* at night) and in the high 50's or low 60's during the day.

For my outdoor trees, I unwrap (or mostly, I "unbury"), and then just leave them open and exposed.  I wish to wait for last frost, but err on the "aggressive" side, because growing season is short up here in these latitudes.  So as a compromise, I exhume (unbury) around mid-April (which is before the last frost), but then if the tips start to leaf out then I cover them with cloth on nights where frost is predicted.  I never have to cover them with a sunshade cloth in this climate.  The only reason I could see to do that would be if the direct sun is too intense by the time they are exhumed, and I were worried about sun-scalding the bark.  Like I said though, up here the direct sun is not that intense in the springtime, so I never have had to worry about sunshading when they're first opened up for the spring.  I prefer to have them break bud to as strong a sunlight as there is, since that'll make the leaves acclimate to strong sun as soon as they start.

Now when bringing out trees that were indoors through the winter/spring... that's another story.  Some of those early leaves are just not robust enough to handle the direct sunlight for very long.  So I position them to get direct sun only for a short duration, then gradually add more time in the direct sun.

Mike   central NY state, zone 5