Douglas Laudenschlager has posted some good information about the considerations you need to make if you are running SSIS on a 64-bit box. This is additional information to what is currently in Books Online, and it’s well worth looking at. Considering that a lot of developers are developing on x86 machines, and deploying to x64 servers, it’s even more valuable. I currently do all my development on a x64 machine, but since the development environment (BIDS) is 32-bit only, some of these items still have impact.
64-bit Considerations for SQL Server Integration Services – Douglas Laudenschlager – Dougbert.com