The Category Grid Template was not allowing me to change to a number greater than 99. However, my category with 102 products was showing 100 of them. Our developer changed to allow up to 999 to be entered, but the actual category page still did not allow more than 100 products to appear. It turns out that 100 maximum was hard-coded. Our developer changed this also to get it to work properly.
I think this should be corrected for future versions.

Tom,

We reviewed the "Grid" category template and there is no hard-coded value limiting the number of items that are displayed (this is configurable via the template settings in the admin). My guess is that either A) the template was hard-coded a long time ago and never got updated during upgrades or B) the template was customized at some point in the past.