From Hotmail...

A freeware program called GetMail will forward Hotmail to another email account.

www.e-eeasy.com/getmail.aspx

First, download and set up GetMail to forward messages from the desired Hotmail account to your Gmail account (make sure the "Mark messages Read" box is checked. Then, go back into your Hotmail account and make sure that any messages you want transferred are:

* 1. marked as Unread; and
* 2. moved from whichever folder they are in, to the Inbox.

GetMail will transfer all the unread messages to Gmail, and the transferred messages will be marked as read in Hotmail.

A pay service called
GTransfer (www.gtransfer.com)
will tranfer and forward for about $5-$10

From Yahoo!

I couldn't find a slick transfer method for Yahoo.
But there are a couple programs that allow you to trransfer Yahoo to a POP mail account. Then you transfer those emails (mbox format) to your gmail

www.marklyon.org/gmail/

the GMail Loader is a graphical, cross-platform, Python based utility that supports two mBox formats (Netscape, Mozilla, Thunderbird, Most Other Clients), MailDir (Qmail, others), MMDF (Mutt), MH (NMH), and Babyl (Emacs RMAIL).

You could use this solution to tranfer your email stored locally (Eudora, Thunderbird, Outlook)