Wow lots of questions flying about things covered over and over in the past. Here's an overview again:
First, 3D ready 120hz projectors require either nvidia 3D vision emitters and glasses (that toggle shutters through an IR pulse), or DLPlink glasses (no emitter required and they sync by generating a white flash on the screen during the blanking period between frames to trigger DLP-Link shutter glasses to toggle) requiring frame sequential 3D (aka page flipping the right eye, then the left eye). And the VIP Theatre emitter and glasses will work. However, no one has successfully used other glasses like Mits, Samsung, etc. as they are meant for other types of 3D such as Checkerboard--where half the pixels are used for the left eye and half for the right. Some of the glasses work at 60hz for checkerboard.
Update: While other 60hz IR glasses might work with the VIP emitter or with their own emitters, no one seems to have tested that successfully yet.
Second, if it is a 120hz rated projector, then it's probably 3D ready anyway and has at least dlplink built in, however requires a PC to use or the VIP Theater if you want direct hook up from a 3D bluray player, cable/satellite TV or game systems. For the PC only hookup, you can watch 3D blu-ray using a non-3D player as long as you have a software player (e.g. PowerDVD Ultra 10 Mark II, or Arcsoft TotalMedia Theater 5), and for games a game driver such as IZ3D or Tridef (search Google). The PC route is where most people are now, and they are moving to a hdmi 1.4a device such as the Optoma 3DXL or VIP Theater to watch 3D without a PC. The PC also requires a high-end video card such as an ATI Radeon HD series or nvidia 400GT--that's a whole different months worth of discussion on other threads...
The 60hz feature of the VIP is an added plus for those who do not want to invest in a 3D ready 120hz projector or LCD. That said, there are many variations of 60hz TVs being tested by VIP users at this moment. VIP is building a list, but it appears that not all 60hz TVs can handle the signal properly due to what is called the need for "frame locking" at 60hz. We have not proved this, but that is the suspicion of the techies on this board.
Hope this helps gain some understanding...