Howcome iPhone can get IMAP, but us ATT U-verse High Speed Internet Access users don't?
I want my IMAP!
IMAP enable you to delete one email message and have all mail clients automatically update their folders, whether they may be your work, home or laptop computers.
POP3 forces you to delete the same email message on each and every computers that accessed your POP account...... Grrrrr. Or configure them so that only ONE computer can do the giant sucking sound of downloading and deleting.
This is an issue with Yahoo! mail, not U-verse internet access. If you use Yahoo! mail with your iPhone, you can use activesynch which in many ways is better than IMAP. see here: http://mobile.yahoo.com/mail/iphone
If you really, really want IMAP, I'd suggest switching to Google Mail, which has IMAP support. And it's free.
And you can have Gmail pull all the messages from your Yahoo mail account and consolidate them in the Gmail account, so you can still get mail that is sent to Yahoo. I did this several months ago and it works great.