I suppose that many people are aware of this, but I was shocked to find it today.
My phone bill arrived and I noticed a strange 0,60 charge for a SMS sent to UK (number +447950080651 ), curiosly at the time when I switched on for the first time my newly arrived Pixi.
I knew initial activation used data traffic (it's also reflected in the bill, but not charged due to data flat rate), but I couldn't imagine that an international sms would be charged to my bill
There is very little information on the internet, I have found this french forum:
Le Forum de PalmPre-France / virtual keyboard
and this german one :
SMS nach UK seit ich den Pre habe - Palm Pre Forum
(used google translator to confirm)