A closer look at one of the fronds.
By the way, the new fronds only show yellowing on the edges, but the yellow expands as the frond grows.

Thanks, Guys and Gals

The only time I have seen this on mine is as a result of a sudden increase in sun exposure when the leaves seem to get bleached by hot sun. Any changes regarding exposure? Maybe inadequate moisture if it is competing with nearby conifers. Also, I just realized that you posted this on the Name that Plant site, well, the plant is Cycas revoluta. (This is generally a healthy, robust, subtropical grower. It does fine in full sun in humid Florida, but I wonder if it is more sun sensitive in arid areas.) You might want to post this problem on the Palm and Cycad forum. Definitely not a question of variegation though!

This post was edited by njoasis on Wed, Jan 1, 14 at 10:38

@njoasis. Thanks for the info.
I think you might be right on both counts.
This summer is a lot hotter than on other visits, and when I checked the side of the cycad shaded by the conifers, there was no yellowing.
It would also appear to be possibly water stressed, as when I checked under the mulch, the ground was bone dry. This was within 24hrs of having about 10mm (0.4") rain. The mulch is quite fine and very compacted, preventing the rain penetrating easily, though it seems to absorb water itself quite nicely.

Looks like sunburn to me too, but check on back of fronds to rule out scale.