While factory ammo has certainly become more available, the .280 is still more of a handloader's cartridge. I fist got exposed to the cartidge in the mid-90's, when I was looking to buy my first true deer rifle. I looked at all the cartridges available, and it came down to the .270 and the .280. I ultimately chose the .280 simply because it was loaded with heavier bullets. I wasn't a reloader then, but ammo was still available.
My first true deer rifle was a Remington Mountain Rifle in .280, and I bought that gun in 1996. I still hunt with it today, and it has taken countless numbers of deer. I have used 140-150gr Core-Lokt's, 165gr Extended Range, 140gr Nosler Partitions, 140gr Win Ballistic Tips, and 139gr Hornady Light Mags in the gun to take deer. It has always been reasonably accurate, and does the job on deer sized game. A handloader can easily load 120-175gr bullets that will take just about anything in North America, and with some of the newer powders, can come real close to a 7mm Mag. My 26" Handi in .280 will easily push 140gr bullets to 3150, which isn't far off from 7mm Mag velocities.
Now, that being said, I am also a fan of the .30-06. Ammo can be found most anywhere, and isn't too expensive. But, if I had to choose one rifle for the type of hunting I do, it would always be my Mountain Rifle in .280 remington.