Multi-Room Viewing is a feature available on Series 2 Stand Alone TiVos. It adds the ability to transfer recorded shows from one TiVo to another TiVo on the same home network. For example, you can transfer a show on your living room TiVo to your bedroom TiVo. Support for this feature for on TiVo Series 3 and TiVo HD units begins in November, 2007.
MRV is a hidden feature that can be enabled on some hacked Series 2 DirecTiVos running software version 6.2x. Hacking is accomplished by patching the tivoapp file to re-enable disabled features; the TiVo must first be modified to run third-party software prior to this being possible. Instructions on how to accomplish this are found elsewhere in this site.