I've bought a new computer because I can't hold up my work while I wait for my older MacBook Pro to return from Apple's repair shop. In the meantime, I've not backed up my iPhone 3G for a week. I plan to sync my iPhone to the new MBP. There's a good discussion of migrating an iPhone to another in a different question -- but it's built on the idea that the old computer is around and involved.
So -- what will I lose or what side effects will I suffer if I just plug my iPhone into my new computer and sync to iTunes?