I unlocked my Verizon storm2, took it to England and used a Vodaphone sim card.
Most things worked, but there were some apps that didn't - facebook, googlemaps, weatherbug for example - they complained that there was an insufficient plan or they couldn't access the network.
Other apps that used the internet were OK, and once I got home everything started working again.
Does anyone have any idea what I need to do to get the storm fully functional abroad?
My guess is that you didn't have a blackberry dataplan on the other simcard/provider.
Some applications require you to have a RIM/BB dataplan next to an internet plan. Most RIM applications require this, 3rd party usually take any connection available.