Google Buzz is now incorporated within Gmail. If you go to Gmail from your Android or iPhone browser you would see a Buzz bar below the inbox bar, just as you would observe in the desktop edition of Gmail. When Buzz was launched, Google had a web app of Buzz for mobiles, but now you could access it right from your inbox.
When you open a Buzz post from your inbox, you can perform all the standard functions, such as liking the post or commenting, just as you can from the desktop Gmail inbox.
You could try it by simply navigating your iPhone or Android browser to gmail.com .