DR is a hot topic these days as more and more firms rely on data that is not stored as hard copy. Virtual Servers are a great way of implementing a DR strategy for a business.
Another area that is gaining ground is in the use of SIP Trunks as part of a DR plan. Rather than completely replacing ISDN or analogue telephony connections with an IP equivalent companies are running with both.
The company will typically keep its inbound traffic running over ISDN and use SIP, with its typically lower cost call charges, for outbound. The beauty is that if the site loses its ISDN connection for any reason the business, with an appropriate level of support, can reroute its inbound numbers to an alternative destination which is has been pre-setup as an inbound SIP trunk. Likewise if the IP connection drops then the business can temporarily use the more expensive ISDN lines.
For a multi-site organisation this is a no brainer as remote locations can also be connected to the company headquarters using the same SIP trunks. The IP interconnect can be an ADSL line, or for larger organisations requiring more trunks and perhaps a higher level of Service Level Assurance, over leased lines.