It takes time for avatars to show after uploading them because the information is cached. The first place they are evidenced is here in the forum and on the wordpress.com category tag pages. After some time passes they will display (1) only when you are signed in and (2) only when you are making comments on other wordpress.com blogs or on your own blog(s) and (3) only on blogs with themes that allow for avatars to be displayed (some themes don’t display avatars). If this remains an issue, then tomorrow you can send in a feedback to staff requesting assistance.
Providing a link to where you’re not seeing your avatar and telling what it’s supposed to look like would be also a good idea. For example, your current avatar is a blue colored face. Is this what it’s supposed to be?