I normally freelance with several different clients at once where I'm
considered a "vendor" so I have to pay all my own taxes, benefits, etc
and can deduct pretty much anything you legally can. A new client has me
as a W2 so they're taking out all the taxes but I don't get benefits of
course. How will this affect what I can deduct?

I read I cannot deduct mileage though I don't see that on the IRS site.
According to Pub 463, as long as it's not a "regular place of work",
they would not be considered commuting expenses and I should be OK.
Since I'm only there when I need to be and can be at other clients as
needed, I'd consider them all to be "temporary work locations".

Is there anything else I should be concerned about or be aware of? I
bought a couple used laptops for this job to handle VS 2008 development
so I would plan to deduct the cost of those as well.