Older thread, I know, but wanted to chime in...
Jelly roll just refers to the look of the roll, i.e., the rolled up fabric. Jelly rolls aren't proprietary to Moda and they can be 2.5", 2", 1.5", 1", and I've even seen 4" jelly rolls. 10, 15, 20, 30, 40 strips and odd numbers are also not uncommon.
Just make sure you read the description on the product, especially on eBay. Sellers there take a lot of liberty on what they'll call a jelly roll - also check the pictures there closely, since a lot of eBay sellers hand or rotary cut their own rolls and may not have the most accurate cuts.