envinyatar99 did a little exploring and kindly pointed out that Fellowship and Two Towers also have been translated into text messaging format.
So we have Pippin in Moria:
P1P&: i in ur m0r14 dropin ur stonz
And to Treebeard in Fangorn:
P1P&: we're in ur forest bein ur frends
As well as Wormtongue in Rohan and Frodo in the Emyn Muil:
Wrmtng: im in ur hall controlin ur king
phr0d0: im in ur mountains climin ur rox
It cracks me up that Treebeard's dialogue cannot be translated into chatspeak!
#119 teh ph3110wshp ov teh ring by Abi Sutherland
Hm, the direct links don't seem to be working now, but scroll up to #119 and #120 from the RotK one:
http://nielsenhayden.com/makinglight/archives/009050.html#190819 #120 teh 2 twrz by Abi Sutherland