Flexis has released a Smartphone version of their
FX100 keyboard. The keyboard works on the SPV, and is available at
OrangeSP.
The keyboard apparently doesn't require the SPV's ROM to be updated, or special keyboard drivers (which is one of the things holding back the
ElekSen keyboard available through Orange). The Flexis is available for £49.99, which matches the current price of the ElekSen keyboard.
So if your fingers are starting to callous at the fault of the SPV's annoying buttons, then you might want to take a look at this keyboard

.