With open diffs, weather it's on the front or the rear, in 2 wheel drive, it shouldn't matter. Up front, it'll just work. It'll probably throw off the steering a little though. Out back, it'll become the drive wheel. It has to spin slightly faster to keep up with the non spare tire. This can throw off the speedometer. Even in full time with a 242, short distances shouldn't matter. I can see long term effects like stretching the chain if you drive it like that for an extended period of time. You would want to keep the transfer case unlocked though. You could damage it in part time with a smaller wheel up front or out back.
1997 ZJ TSi - 5.2L, 242, ~4" of IRO lift, IRO short arms & adj. TBs, JKS Discos & BPEs, DT3000s, Aussie out back, sliders, OEM skids/hooks/hitch, 31" Duratracs, 15x8 Stealth Crawlers, Niner grille, e-fan, Magnaflow stuff, HO alt, "mean eyes", tinted signals & tails, clear corners, sound system, cloth seats
1994 Caprice - "SQL Lab", HO charging system, SS suspension, show car in progress, some tasteful
2014 Silverado 1500 - DD on order
2010 Terrain - wife's DD, bone stock
2010 Gary Fisher Utopia - Black Ops platform pedals, SRAM X.9 shifters, BB7 calipers/G3 CS discs, NightRider Rebel 3.0 computer
Black Jeep Society