As project codename Astoria has new name "ADO.NET Data Services Framework " and it is part of ASP.NET 3.5 a.k.a ASP.NET futures it has its place on asp.net site.
There are plenty of samples and descriptions what is it and how to use from client and server site.
If you struggle what is REST and how it is different than well known web services take a look at this web presentation: Reconciling Web Services and REST Services.