Here’s the list of free ASP.NET 4.0 and vs 2010 Beta hosting providers currently . There may be few providers missed,would update as i come across them.Alternatively you can add them in comment too 
1. MaximumASP is offering a free hosting account so you can get started with ASP.NET 4 and Visual Studio 2010.
On this account you can test ASP.NET 4 applications in a hosting environment and try out the new publishing features with Visual Studio 2010 and the Microsoft Web Deployment Tool.
- Windows Server 2008 R2 / IIS 7.5
- .NET Framework 4 Beta 2
- 1GB disk space
- 50 MB SQL Server 2008 database
- MS Deploy Access
- FTP over SSL Access
for more details visit : http://aspnet4beta.maximumasp.com/
2. ORCS Web is offering free ASP.NET 4.0 beta hosting until the end of October. Hosting plan is called “VS2010 and Web Deployment Tool Beta Program”. If you are interested in it then please feel free to sign up.
Beta hosting plan contains following features.
- Windows Server 2008 / IIS 7
- Web Deployment for publishing (no FTP)
- ASP.NET 4.0 (or 2.0/3.0/3.5 per request)
- 200MB web space
- 100MB SQL Server 2008 space
- ORCS Web support.
Link : http://www.orcsweb.com/hosting/vs2010beta.aspx
3. DiscountASP’s free sandbox hosting program is offered as an open beta and has limited space.
Interested developers are welcome to sign up at http://labs.discountasp.net.
