The upload limits in the new Drupal 7 file module seem to be set on a per-field basis. When doing this, there is not enough checking of the limits in PHP. It currently says something like "If left empty the file sizes will be limited only by PHP's maximum post and file upload sizes (current limit 25 MB)."
It should say something like: "If left empty the file sizes will be limited by PHP's maximum post (64 MB) and file upload (25 MB) sizes"
It should also check if you are entering a size larger than one of these values and issue a warning (as upload.module does in D6).
Finally, it should be possible to set a default value on a site-wide basis.