The reason nobody has commented yet is because its kind of a silly question because there is no tablet or cell phone with up-gradable RAM as its one of the things that are associated with embedded systems/SoaC; it really isnt that dumb of a question however considering things like XBox's, PS3's, Mac Mini's, etc - the thing with the highly embedded systems such as cell's, tablets, routers, etc is that every component on the board was chosen to fit a specific condition - they use as little chip as possible to keep costs or purchase/mfg, power consumption/heat among other factors as low as possible as to make them marketable and profitable. So with these 1GHz class phones and tab's, since they all are basically mini hypervisors for small programs (5MB +/-4MB) on an OS that has a very small footprint, they can make that 512-1024MB of system mem go a LONG way. in short, dont fret to much about it - if you want to check out your true resource usage on android or any other linux system, just open a terminal and use the command:
top
