Giffgaff will start supporting Blackberrys properly around the new year (at last estimate).
In the meantime, click the link below and have a look at the guide:
Giffgaff will support the full BlackBerry services ( i,e BBM/BBI ) but not as yet, The latest is late this year / or maybe early next year but no exact date as yet!
Keep upto date here: http://community.giffgaff.com/t5/Blog/bg-p/giffgaff
EVEN FOR NOW YOU COULD USE THE GIFFGAFF SIM JUST FOR CALLS/TEXT/OPERA MINI ETC ?
MMS DONT WORK AS YET ON BB USING GIFFGAFF
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
Blackberry Video tutorial for setting up opera mini - http://www.youtube.com/watch?v=e8MJGumj224
Unlock your blackberry for free - http://www.unlocks.co.uk/unlock_blackberry_free.php