When trying to build using VS2008 and Windows 7 I ran into a couple of erros. Here's what they were and how I resolved them.
Error 1 Metadata file 'C:\CodePlex\ssisUnit\SsisUnitDesign\bin\Debug\SsisUnit2008.Design.dll' could not be found
Error 2 The command ""C:\Program Files\Microsoft SDKs\Windows\v6.0A\Bin\gacutil.exe" -u SsisUnit2008.Design.dll" exited with code 3.
895 9 SsisUnit.Design_SQL2008
Modify the Project Properties of SsisUnit.Design_SQL2008. On the Build Events page I changed the path from: "C:\Program Files\Microsoft SDKs\Windows\v6.0A\Bin\gacutil.exe" to "C:\Program Files\Microsoft SDKs\Windows\v6.1\Bin\gacutil.exe".
Also, there are a lot of references to file paths C:\Projects\... throughout the solution. I saved my solution to C:\CodePlex so those all needed changing too.