My experience so far = is not extensive. I just set up a new GMail account so I can have my herringlaw mail [which is full of spam which is caught by SpamSieve on my computer but won't otherwise be caught if I set that account up to be checked on the iPhone] forwarded to it and then to be able to download my herringlaw email via iPhone via GMail account....at least the GMail spam filter will help.
I'm still a bit confused about quitting the apps but do know the home button does that = of course, I haven't read any material and it might be good to do that....or at least watch the iPhone tutorial. I filled up the 8G with music and videos and have used it some - I found out that I could create a playlist [click and drag type, not smart] and just clicked all my 5* pieces and purchases - that's 12G and now I'm going thru and deleting from that playlist what I don't want or need then the only thing that needs to be synced is this playlist...this works great.
Tonight.....We just had dinner and I was going to put on the stereo but my favorite music is also on the iPhone so I just brought it upstairs, and played background music during dinner then we called our daughter....not that I couldn't use my iPod or stereo just as well, but it was a nice little change and certainly when one is not near the stereo or other source, it's an option = no need for speakers....nothing fancy about speakers and the music aficionados might not be happy with it but it'll do in a pinch. For now I have my Verizon account set to forward to the new ATT number = still need to shut down the Verizon account and negotiate the family plan stuff. All in all though it'll save my husband alot of $ and it'll cost me the same for more minutes [450