Paul Pierce grew up in Oakland, so I don't think any bridges would be burned between he and the Celtics for this trade. GS is a young up and coming team. Here's my idea
Paul Pierce to the Warriors for Klay Thompson, Jeremy Tyler, GS 1st round pick and Kwame Brown's expiring.
Celtics pick up a nice wing scorer in Thompson, a project in Tyler that a lot of people wanted last year for his potential, and a first round pick that should be top 20. Salaries are a bit off so might have to add someone in or replace tyler with Udoh or throw in Dorrell
GS is a legit threat, if they can somehow pick up a Javales McGee type that can run with their team and play defense in the paint they could be dangerous. Curry/Monta/Pierce/Lee is plenty of scoring and they could be that kinda team that's a 6 seed and makes it to the WCF