activesync is working for some people and some not. i dont think microsoft/hotmail has converted all their existing accounts to support it yet?
i've been waiting for this and some blog user comments are showing that some people are getting it to work and some arent. you can try and see if its working for you.
setup the mailbox as an exchange account,
username: your full email email (hotmail.com, live.com, etc.)
password: your pw
domain: m.hotmail.com
and i think ssl should be on. (not sure though)
after setting it up and your getting a password error, its not active on your account yet.
there was some talk from a microsoft admin on the hotmail/live blog that they are fully implementing activesync by the end of summer.