As stated in http://www.boutell.com/newfaq/misc/urllength.html, HTTP query string have limited length. It can be limited by the client (Firefox, IE, ...), the server (Apache
The confusion around GET is a browser limitation. If you are creating a RESTful interface for an A2A or P2P application then there is no limitation to the length of your GET.
Now, if you happen to want to use a browser to view your RESTful interface (aka during development/debugging) then you will run into this limit, but there are tools out there to get around this.