I'm still having this problem. On my user page here I see the new avatar in my signature at the bottom of the page (a manual link to images1.wikia.nocookie.net), but the old one is still being displayed everywhere else (e.g. the user info/edit count, the login at the top-right, and to the left of where I'm typing this message right now).
I've tried: a) clearing the browser cache, b) checking on two different computers, and c) re-uploading.
Your avatar images all match for me.
Guess it's my problem then, after trying three browsers and two computers I wasn't sure what to think. I'll try deleting the temporary internet files and such again. Thank you very much!
Addendum: Upon further investigation I think I discovered an error - the old avatar was a .jpg file and Wikia seems using "150px-5308644.png.jpg" (which displays the old avatar when opened in a new tab) when it should be "150px-5308644.png" (the new avatar). I've used Special:Contact to request help.