Many businesses I work with (some quite big) are still using IE6.
Where I work, we’ve been using IE 7.0 since July 2007, mostly because it’s been tested to work with the company intranet and because we needed the ability to view multiple intranet sites in tabbed browsing mode. There are plans to start rolling out IE 8.0 starting early 2010, mostly because by the end of 2009 all of the desktop machines in my workplace will be running machines with Intel Core 2 Duo CPUs, Windows XP Professional (SP3), 2 GB of RAM, at least a 100 GB hard drive (most of the storage is done on server machines), and Office 2007, which makes it a perfect candidate for IE 8.0 rollout.