Microsoft has released the SQL Server 2008 R2 – Service Pack 1 (Version# 10.50.2500.0, Released: 7/11/2011)

You can right away download the files from here [Download Link]

Download Microsoft® SQL Server® 2008 R2 Service Pack 1

Download Microsoft® SQL Server® 2008 R2 SP1 – Express Edition

Download Microsoft® SQL Server® 2008 R2 SP1 Feature Pack