The chart below shows the results obtained for a reanalysis grid point close to Fairbanks: the black line depicts the annual mean pressure gradient, and the colored lines show the mean gradient in three-month seasons. It is interesting to note that the mean annual gradient was slightly lower than earlier norms for about ten years beginning in 2000, but it was slightly higher again in 2012 and 2013. The largest decline from earlier years occurred in winter and fall, whereas spring and summer showed no significant change.
The drop in mean pressure gradient since 2000 is consistent with lower mean wind speeds at Fairbanks, suggesting that the wind speed really has slackened in recent years. However, note that the annual pressure gradient did not begin to drop off until 2000, whereas the reported wind speed dropped off quite precipitously in 1998, so I think it's likely that there is also an equipment or measurement change involved in the wind speed history. Of course, we should remember that the surface wind speed is also affected strongly by the inversion and stability characteristics of the air near the ground, so the pressure gradient is not the only determining factor.
The spatial scale of the pressure gradient change is illustrated in the map below, which shows the difference in mean gradient since 2000. Most of Alaska stands out prominently as having a reduced pressure gradient, while the Arctic Ocean has experienced higher gradients in recent years. The changes in the lower 48 are rather small, except in New England where weaker gradients are consistent with Brian's map showing weaker wind speeds.