Giffgaff will support the full BlackBerry services ( i,e BBM/BBI ) but not as yet, The latest is in the Autumn time - September to November/ or maybe early next year but no exact date as yet!
To Keep upto date here: http://community.giffgaff.com/t5/Blog/bg-p/giffgaf
EVEN FOR NOW YOU COULD USE WIFI TO USE BBM/BBI AND USE THE GIFFGAFF SIM JUST FOR CALLS/TEXT/OPERA MINI ETC ?
How ever you can still surf the internet/call/text until giffgaff fully supports it by checking out the links below:
How to Giffgaff a Blackberry - http://bit.ly/giffgaffblackberry
Blackberry app world & Blackberry Browser - http://bit.ly/ecXpIK
BBM and BB Alternatives - http://bit.ly/ekN2eN
Facebook & Blackberry - http://bit.ly/igz4hl
Why can't I browse the Internet? - http://bit.ly/i7dGhk
Blackberry smartphone Apps list - http://bit.ly/ggblackberryapps
Blackberry messenger alternatives - http://bit.ly/bbmaltgg
Advanced Blackberry usage - http://bit.ly/bbusagegg
Blackberry Config Tip - http://bit.ly/ggconfigbbtip