Almost all of to days firewalls include some type of vpn or virtual private network access. The firewall will have software clients or you can download them from your firewall vendor. This can include ipsec or ssl, you can also use pptp which is built into windows. They are fairly easy to set up or will require about two to three hours of consulting time for a smaller company. This will allow them access to local servers and resources.
If your employee commutes 16-20 miles each way a day that's about $5.00 a day in gas. If the employee is 100% virtual that's a saving of $1250 a year or 500 gallons of gas at $2.50 a gallon. Plus the countless hours spent in the car probably sitting in traffic a good deal of the time. Providing an office and resources in the office is expensive, rent, energy and resources. Yes there are costs with going virtual and telecommuting but in the long run it is much cheaper as long as you are able to evaluate and maintain employee performance.
You can also double the efficiency of a car by adding one passenger.
We need to act fast, adapt and start to take heroic measures now and conserve what we have because the new technologies are just not going to be ready quick enough. Inflation is coming across the board. Our whole economy is based on cheap efficient energy and it will end soon. It's a fact that we just are not going to be able to afford to drive as much and we will need to off set our rising cost for products and services that we use everyday that will be inflated because of rising energy costs.
Mainstream telecommuting as I see it is probably one of the best options to conserve because we just flat out get gas consuming cars off the road. Another benefit is that the air will be cleaner in most metropolitan areas.