The update weighs 237MB, which is the whole OS as usual, and is here on time, as Jobs announced it would be available sometime on Friday.
Get it now through iTunes
or from the following addresses:
For an iPhone 3G:
iPhone1,2_2.1_5F136_Restore.ipsw
For an iPhone 1G:
iPhone1,1_2.1_5F136_Restore.ipsw
