I got my G1 and had to sign-in with a Google account before I could even use the phone, kinda annoying. Then, it used Google Mail for my contacts list (meaning everything I had already uploaded to T-Mobile's online contact list was unavailable). It also automatically synced my email and calendar to the phone using a special G-Mail app, but I had to add my Yahoo account (my main email) to a separate Email app (yeah, two apps to check email, thanks).
My fiancee, on the other hand, was able to use all the same features on her blackberry (Google Maps, GMail, GMail contacts and calendar, etc...), no problem.
Long story short, any decent smart phone can use any of Google's services, they don't have to be (nor should they be) tied into the damn OS, especially if you don't want them.