Update 06-15-2014: the road is paved all the way to the trailhead and there are also now facilities and a nice large ramada but still now water.
With the new Trailhead, you can now put an address in GPS which makes it much easier to find it. The GPS Address is:
23015 N 128th Street
Scottsdale, AZ 85255
On my first visit I took 128th Street south from Dynamite. This is not desirable - there is a long unpaved stretch that is deeply rutted in places.
On my second visit I took Happy Valley east, then right on 118th, following helpful signs to the Tom's Thumb trailhead. Eventually you do turn right onto 128th Street, but it is all paved from that point to the trailhead. Much better.
If you put the trailhead address into your GPS, it will take you the wrong way and you'll drive 3 miles and three more back once you realize. The closest street address is 2500 N 128th St at 12800 E Ranch Gate Road. Once there turn right and drive a little ways, you can't miss it.
Also the trails are all well signed, except the climber's path to the peak. The path is on the left about 100 feet or so before the sign marking the juntion of the East End trail. That trail doesn't actually go to the summit. So if you get to the East End trailhead from Tom Thumb, turn around and walk a little ways to find the unmarked trail to your right.
I scrambled up from the trailhead point to a saddle and false summit... fun & challenging, but not really necessary.