InfoQ published in December 2007 a list of vendors which mentioned their interest in creating ADO.NET providers which support the Entity Framework. David Sceppa, a Microsoft ADO.NET Program Manager, has recently announced those companies and their offerings on his blog:
Core Lab. Being the first company to offer an ADO.NET provider with Entity Framework support, their provider includes connectivity to Oracle, MySQL, PostgreSQL and SQLite databases. More information from Core Lab: ADO.NET Data Providers and dotConnect for SQLite.
IBM. IBM has announced the release of LINQ Entity Framework Beta for DB2, IDS and U2 servers and can be downloaded here. Limitations: "This is the Entity Framework Beta 3 and Data Server clients (ds driver, runtime client or client) at V9.5.0 levels only. The beta will also work with DB2 Express-C 9.5. The beta updates the existing IBM.Data.DB2 provider, thus any V9.5 fixpacks or updates to the Entity Framework after than beta 3 will not work with this beta."
Npgsql. The beta 4 provider for Postgresql is available for download.
MySQL.David Sceppa says he has demonstrated the functionality of the MySQL provider during the recent MySQL conference in Santa Clara, but the provider is not yet available. They will probably release it soon.
The Entity Framework has reached the Beta 3 milestone, and is intended to decouple the developer from the underlying databases he is using, accessing the data stored in them as domain objects. More information on the Entity Framework can be found in MSDN.