ObjectSpaces introduces a mapping layer that separates the business logic from the data access logic to reduce the amount of code to maintain.  It's a declarative mapping between objects and relational tables.  It makes sense when you have a strong or large business logic layer.  It will be available in Whidbey.  They will also have a nice User Interface in Visual Studio to help with the mapping.  I've heard from some ThoughtWorks friends that it's not as good as the Java versions or Neo, an open source product from ThoughtWorks (this guy may have been biased ;)

It works with mapping files to tranlsate from an object query/update to a SQL query/update.  The idea is that objects are responsible for saving their own data and can just call a .Persist method to save the data to the database.  One of the examples is showing how to use GetObjectSet to execute query strings against the objects.  It's a new query language called OPath that lets you write select statements such as this to return data:

It's being given by Luca Bolognese who has promised that his goal is to avoid PowerPoint hypnosis and aim to make sure that no one falls asleep.  He's Italian (yes, really) and a very funny speaker.  However, his accent can sound funny.  He's reading out SQL statements and adding an 'a' to every word, so when he's reading SQL statement it sounds like 'selecta ... froma ... exista'

Classic quote:  Someone asked why they ar eusing OPath rather than XPath.  He said 'we used XPath in the prototype and gave it to the group of programmers, and they came back and said it was too hard.  So we did a search and replace to switch the slashes with dots and they loved it'.  Actually it appears that the two are different problem domains.

I'm sitting with Peter Provost (by chance, the photographer of many of the photos in my photo blog roll), soaking up the blogging energy that he's emitting.  He's actually writing the source code as we see it (a true touch typing programming god!) so perhaps he'll post it later (Peter's notes are now available).

Update: Paul Wilson left a comment pointing to more examples in his article on ObjectSpaces.