Gmail as a CRM (Customer Relationship Management)?

Luca Reginato at his blog has written a piece on how to use gmail as a CRM. He have used many of the enterprise CRM solution like Siebel and salesforce.com etc but those did not give him good experiences. He came up with an idea - can he apply the requirements on a CRM and fits into Gmail?

… Gmail gives you thee dimensions in order to manage your customer relationships,
label, priority, and time.
label: all you need are 4 labels: info, lead, todo, done.
priority: the star stamp, don’t abuse it, if you thinking that you have more than 3 high priority issues you’re misjudging.
time: gmail intrinsically add a precise timestamp to all your conversation, and when you search your valuable customer informations, it shows you the results in a perfect LIFO - reverse chronological order.

Read his instruction and thoughts on this topic. What do you think of this idea? I think it proves the concept but it has some disadvantages - Privacy would be the first thing that I worry about. Multiple users access would be the second one.

Gmail as CRM (Customer Relationship Management)