Google [GOOG] has rolled out email delegation to Gmail users. Previously, the service had only been made available to Google Apps email users.
What the email delegation service does is lets you have someone else be able to log in to your email account. This could be handy for those who run both private and business email accounts which would allow them to use both accounts at the same time. Other uses could include letting an assistant at work access your email so they could manage email for you.
At the moment the service works between either Gmail and Gmail accounts and you cannot use Google apps email across domains. So if you run both you own domain on gmail and have a regular gmail address, you wont have access to this service.
If you do just use two regular accounts though then this is certainly a handy feature to use. To activate it, just log in to Gmail, click Settings, Accounts and then in that section you can enter the other email address of someone to share the account with (ie, yourself, family, secretary).
More details at the Gmail Blog.
That’s pretty cool.