yup, i'm in the lab today as well. Cells dont take holidays off . But being a grad student means i staggered in a bit late, and am plannin to jet a bit early.
The boss is pretty good, gives us a couple of weeks vacation during the year, then usually no one is around during xmas time. As for single days off here and there, he doesnt mind too much as long as you get your stuff done before you leave and that you dont abuse the system.
Essentially it boils down to "take your week in the summer, take xmas off, and if you need a few days here and there throughout the year, then go ahead."