In VS 2010 you should not create seperate website for mobile, but a standard ASP.NET website with pages designed for mobile best output.
Now when you develop a mobile website it is very important from marketing point of view that you share same domain for your standard website as well as mobile website.
For e.g. your standard website domain is www.standard.com, there are two things you can do when any user is browsing this domain from mobile device
1) Detect if request is coming from mobile device redirect user to http://standard.mobi
2) Detect if request is coming from mobile device redirect user to http://www.standard.com/mobile/
Above are two ways of redirecting the user automatically to mobile optimized pages instead of asking user to browse the mobile website.
To achieve above it is very important that you detect the mobile request perfectly.
Please take a look at http://51degrees.codeplex.com. It is an ASP.NET open source module which detects mobile devices and provides auto redirection to mobile optimized pages when request is coming from mobile device. It makes use of WURFL mobile device database. For redirection there is no need to modify existing ASP.NET web application pages.