We were thinking about organizing our BIG project this way:
\\trunk [CompanyName] [Product1] [Project1] CompanyName.Product1.Project1.csproj
An alternative that I've used is to have all my solution files in the same directory.
\trunk [CompanyName] CompanyName.Product1.sln CompanyName.Product2.sln [Product1] [Project1] CompanyName.Product1.Project1.csproj [Project2] CompanyName.Product1.Project2.csproj [Product2] [Project3] CompanyName.Product2.Project3.csproj