If the 4Runner is on the typical Toyota product life cycle, then '07 will not see any significant changes, if any at all compared to the '06. By typical Toyota product life cycle, a brand new and major redesign every 5 years, year 3 has engine/powertrain upgrades and year 4 there's a minor facelift.
This holds true for most Toyota's that have a 5 year life cycle. The current Camry in its 5th gen: 2002 new body style, 2004 V6 SE trim got the 3.3-liter 3MZ (although later model 2003 V6 models got VVT-i and 5 speed), 2005 got the face lift, 2007 introduction of the 6th Gen. The 4th gen 4Runner, introduced in '03, '05 V8's got VVT-i, V6's got a 5 speed and in '06 it got a face lift.
IMO, as others have mentioned, the waiting will never end since it only gets better. In '03 I waited until the '04 Camrys arrived, so I could get the 3.3 V6, but then '05 got the update. But I never thought twice about holding out for another year to get the '05 Camry. I think I just lucked out this time around being able to get the '06 4R with the minor update.
Good luck, if you can hold out and wait, more power to you. I'm getting anxious and impatient waiting for mine. I wish it could get here ASAP.