Developers should be getting ready for Sandboxed Solutions in BPOS SharePoint 2010. 

Here's some background:

One of the ways we can think about Sandboxed Solutions in relation to SharePoint 2007 is that they are very similar to 20 site administrator templates available in the Fab 40.  These were templates site administrators could simply upload and then use to create new sub-sites.  In SharePoint 2010 Sandboxed Solutions are actualy WSP's that site administrators can upload.  IT can centrally control what it decides site administrators can deploy and then carefully control how these solutions run and the resources they consume.  That makes them an attractive alternative to server side solutions that are deployed to a SharePoint web applications and activated as Features on Site Collections.  Because BPOS 2010 supports Sandboxed Solutions developers should be starting to think about -

1. How they design, develop and deploy if they are a developer internally at an organization
2. How they will design, develop, deploy, market and sell if they are an independent developer or an Microsoft ISV

Link for Developers on Sandboxed Solutions and BPOS SharePoint 2010

A good place to start is Channel 9 from Microsoft.  I highly recommend that you take a look at this link and watch / read the material referenced therein.

More to come on SharePoint 2010, BPOS and Sandboxed Solutions.

http://channel9.msdn.com/learn/courses/SharePoint2010Developer/SandboxedSolutions/