Hi @semmelway, I was not able to reproduce this issue. I used the following code, derived from [node:1059] (which has a few inaccuracies, written as it was for API v1. Current docs are at [node:9708].
Note, this code requires https://github.com/themattharris/tmhOAuth
<?php
require ‘tmhOAuth/tmhOAuth.php’;
$tmhOAuth = new tmhOAuth(array(
‘consumer_key’ => ‘CONSUMER_KEY’,
‘consumer_secret’ => ‘CONSUMER_SECRET’,
‘user_token’ => ‘USER_TOKEN’,
‘user_secret’ => ‘USER_SECRET’,
));
// we’re using a hardcoded image path here. You can easily replace this with an uploaded image-see images.php example)
// 'image = “@{$_FILES[‘image’][‘tmp_name’]};type={$_FILES[‘image’][‘type’]};filename={$_FILES[‘image’][‘name’]}”,
$image = ‘./LARGE_IMAGE_FILENAME.jpg’;
$code = $tmhOAuth->request(‘POST’, ‘https://api.twitter.com/1.1/statuses/update_with_media.json’,
array(
‘media[]’ => “@{$image}”,
‘status’ => “A pithy comment on my photo.”
),
true, // use auth
true // multipart
);
Using this code I was able to post a 3.1 MB image without issue. See https://twitter.com/c_r_w/status/347772846833016832. 
I was not able to try an upload with Android, it may be worth checking out the mobile forums on that issue.
