This site has some good info for Developers and I think this one is really good - it has input and webcasts from the guru's Frederick Chong and Gianpaolo Carraro.

Read more about what BT are doing here. Leaders from BT were at our Partnering for the Future dinner with some of our innovative partners this week and talked about their vision for Value Added Services. BT are looking for ISV's with 'SaaS ready' solutions for Small Businesses to go on their BT Application Marketplace. You can read a bit more about the criteria for this in the presentation from our recent ISV Innovation Day.