Just heard a piece about Thrive on Radio 4's You and Yours. I'm sure it will be on the listen again thingy later. All about the charity and their plans for a Chelsea garden this year :)
'Thrive' were also discussed during the week on R4
As you say it was about the small urban garden for the Unexpected Gardener that they're creating for the Chelsea Flower Show which should give the charity a lot of well deserved publicity. :)
http://www.thrive.org.uk/thrive-at-rhs-chelsea-flower-show-2529-may-2010.aspx
The garden at Chelsea sounds great - be interetsing to see it (or pics of it!)