I'd like to put the IT departments perspective on this story, because although I understand the comments written here it's not quite that easy.
Forrester recommend that IT staffs be encouraged to learn what tools the staff want to use and facilitate their use..
Ok, lets take Dropbox, or Skydrive, or Google Drive, or Box.net, or any one of 20 or so similar systems where staff can hold company data, potentially restricted in the cloud, a space this week publicly shown as been not the best place to hold anything (6.5M Passwords leaked at Linkedin and issues at Last.FM) Dropbox itself has been shown to leave the doors wide open, leak data and passwords. Just because someone wants to be using those nice cloud based apps doesn't make them always viable.. Cloud based systems are also a great entrance for malicious software into a company, files shared around work colleagues and mobiles.
Forrester also suggest virtual technologies to provide a good solid windows Environment. I'm not sure if Forrester have noticed that the world is in a recession ans while the IBM's of the world can afford to do this to get a VMware or Citrix infrastructure in place is expensive. Sure this could be done off site in the "cloud" but again, security is not in your control. for many companies just staying afloat is a problem enough...
Forrester have mentioned the potential cost savings however I belize long term this is a misnomer because yes your are saving on hardware costs however even if you relax the security, use the apps the second you install anything on an employees PC you like it or not become support for EVERY issue on that PC. That costs the time and money of your IT department, while they are explaining for the 2000th time that installing the IT App on the users iPhone didn't stop Angry Birds working or introduce the keylogger on their PC the basic fact of the matter is you start using home PC's for work, you end up supporting them. If the IT department usually standardises on a single PC make, it's easier to support it, they will have images which contain the software a dept uses preloaded, bosh, problem solved, you can't do that to the Sales Reps's PC with 50,000photos also stored on it which have never been backed up.
And as for the suggestion that some companies are still using XP being a bad thing, having seen users migrate from XP to 7 and Office 2003 to 2007 is not always pretty, more investment in training, ensuring EVERY person is using the updates software making sure spreadsheets, macros and presentations all work properly in the updated office or the accounts app works on the Windows 7 64 instead of XP 32 is important, takes time and you'd better believe if you don't get EVERYTHING working as the IT department you are going to have no end of complaints. Complain as they might people don't like change. They will sit there and tell you in the pre change meeting this is all good, they understand why, its a great idea.. it rarely is...
A work PC is a tool to perform a task for a company, it is maintained and setup to do that task which in turn you are paid for. Software is used which allows people to perform that task and while upgrades and the cloud are pretty buzzwords, and i'm the first to agree there are some great commercial services out there, it's in it's infancy and needs proving from a corporate space. In todays business with so many entry points for malicious software into the system, data leakage out of it your data is important. Users prove time and time again that as a collective they are not to be trusted even the most tech savvy take shortcuts which put entire systems at risk.
I would put this too you..
In a world in recession, where keeping your job means more than it used to, with so much unemplyment out there, are you willing to risk your company's data and IT system to a world where the iPhone is used, a cloud based system is put in place if it could mean that your company is hacked and you lose your job because someone in some department opens an exe which shows dancing cats? Or would you keep to using that same old kit, and have your pay turn up into your account each month?