This day has been coming for a long long time - in fact, Webmasters have been asking for an easier and more secure way to grant access to their Google Webmaster Tools area since Google Webmaster Tools launched.
Jonathan Simon announced on the Google Webmaster Central blog that those controls are now here.
You can give both "Full" and "Restricted" access.
- Full Access - Granting a user "Full" permission means that they will be able to view all data and take most actions, such as changing site settings or demoting sitelinks.
- Restricted Access - When a user's permission is set to "Restricted" they will only have access to view most data, and can take some actions such as using Fetch as Googlebot and configuring message forwarding for their account.
Here is how a user knows if they have "restricted access":

To add/edit/remove users go to the home page when you click the "Manage site" drop-down menu you'll see the menu option that was previously titled "Add or remove owners" is now "Add or remove users." Selecting the "Add or remove users" menu item will take you to the new User administration page where you can add or delete up to 100 users and specify each user's access as "Full" or "Restricted."
I recommend everyone remove change however they did this before and switch to this method asap.
Forum discussion at Google+.

Comments:
Ken Fobert
03/06/2012 02:43 pm
Good to see Google finally got around to this. My last job was an in-house SEO specialist at a corporation but we outsourced our link building. Our link building team was always asking to have access to our webmaster tools, but as everyone knows when working with big companies, they are very hesitant to give access to anything like that. This would have been perfect for us a year ago. Either way it's great they have finally added this feature.
Digital Climb
03/07/2012 02:20 am
Glad to finally see this level of control. Sometimes it's the small things that count.
Nicky
03/07/2012 08:51 am
Yes, I`ve experienced that problem as well. No one wants to give their most important information away, especially their analytics account. Luckily Google is doing the best they can to change. it just takes time.