I just noticed that Twitter updated their Tweet button. The changes are subtle, but are an improvement. The changes I noticed were:
• Updated Icon — They’re using a bird with a larger wing
• Color Change — The button is gray instead of light blue
• Button Size — The button width has been increased from 55px to 56px.
• Type Color — Has been updated to black
• Counter Width — Has less padding, and has been reduced overall.
I haven’t had a chance to compare the size of the image sprite, but I’m going to assume that it’s smaller.