I want to build a metro style win 8 app which needs to access a local database (installed on the users pc) of information such as sql express.
The current beta builds of win 8 dont seem to support that. Has Microsoft released any info on whether this will be supported? Something like ado.net, entity framework, linq sql?
No, Windows 8 Metro style apps will not support connecting to a local database. That is to say, you will not be able to use a kind of connectionstring where you can say connect to server X. This has to do with the "Market store" principle that applications should work out of the box without configuring a database connection.
Probably there will be support for a local database as in Windows Phone 7 (SQL CE) with Linq to sql on top of it.
If you would like to access a database that's in a central location, than you will have to expose the data from the database with webservices which can be consumed by your metro style application.