Well, in many ways yes. Back in the day of 727's aircraft were built for speed and it was a marketing point. Now they are constructed with a greater eye toward revenue. Hence the popularity of the 757 which was built with the idea of carrying as many passengers as possible with greater efficiency than existing medium/long haul aircraft like the L1011's and DC10's, although the aircraft is pretty powerful.

Airlines have also started using former shorter haul aircraft like the A320's and 737's on longer routes. It is now common to do transcon on these variants.

Aircraft are flying at higher altitudes as well compared to the 1980's for greater efficency. Not unheard of anymore to do 40,000 in a 737 on a run like PHX to MCI. I would guess that more crowded skies also have much to do with this.

And many in the airline industry have started to speculate that the future lies in connecting short haul routes on commuter aircraft like the CRJ and ERJ series going into smaller airports...dropping passenger loads, increasing fuel costs and major airport fees are starting to factor in airlines trending towards this type of routing.

I am not sure, but I think FMS's all over are being tweaked for efficency factors down to the last drop. If this means slow and high instead of fast and low, the pilots are pretty much obliged to comply. It all depends on distance, wind and passenger loads as well as scheduling. Nothing more wasteful than sitting on the ground waiting for a gate because you got there early..or late. One engine taxis are also becoming more common although i am not sure how this saves fuel, you just put more load on one engine.

American Airlines claims that when all is said and done, a single flight doesn't generate much more than a few hundred dollars in revenue. Saving a few gallons of fuel makes ALL the difference.