I don't think there are major issues doing so but for simplicity i think you need to think of one machine as your primary. You could lose some info in the process of syncing with both by not knowing what goes where.
One of things with the iPhone is that it mainly has to be synced with one computer (without work arounds). So if you sync with one computer and then try to sync it to another, it will overwrite the other stuff from the last computer. If you are looking to make sure your contacts, calender and stuff stay synced between all 3 then it would be a good idea to try mobile me. So when the info is updated on one of them, it flows to the other devices as well. It's a little more challenging to make sure your media stays synced. But purchased stuff from the iTunes store can be synced easily by choosing file and then "transfer purchases". As long as your logged in with the same account, you'll be good to go there.
The long workaround I found is below. I used this in the past, and it worked. There may also be a jailbreak app out there as well. Try the below and see if it works for you as well.
