First Up... If you want to find out what Wavefront Mapping is all about head over to the Society of Robots Tutorial. It has a great wtite up and its where I first learnt about it.
Basic's done, So lets talk about Map size limits.....
The Arduino 2560 & 1280 both have 8k of SRAM (where the map is stored)
I'm using an array of Int's, each Int is 2 Bytes, so max size would be the square root of 8k / 2.
8192 / 2 = 4096
Sqaure Root of 4096 = 64