While working at an large utility organisation that has an Enterprise deployment of MOSS; they had their MySite Functionality turned off for all users. Now while I agree that there is a considerable amount of resource required to implement and manage the MySite functionality in SharePoint, it does have it’s benefits:
One approach I find useful is to phase / incrementally deployment of MySites across the Enterprise. The following will show how you can achieve this:
1. Within the Active Directory (AD) create a new group called “SharePoint MySite Users” or something similar, this should be created as per your corporate policy;
2. Add the users that you plan to initially grant access to MySites to the newly created Group. You can also add existing AD Groups to this groups; for instance if you wanted to add the IT department you could add a AD Group that contains all members of that Department;
3. Launch your Central Administration console and select the Shared Services associated the SharePoint Site. From the Shared Services Home page select Personalization services permissions;
4. This will launch the a permissions page where you can grant rights to various personalisation services. You will notice that by default the NT AUTHORITY\Authenticated Users have been granted Personal Features and Personal Site rights. We are interested in the Personal Site rights. We need to remove these rights from the Authenticated Users groups. To do this select the Authenticated Users, and click Modify Permissions of Selected Users;
5. On the Modify Permissions page deselect Create Personal Site and click Save;
6. From the Manage Permissions page select Add Users / Groups. On the Add Users / Groups page enter the group that you created in steps 1 & 2. You can use the people picker functionality to help find the group. Check the box next to Create Personal Site and click Save;
7. You will now see that the SharePoint MySite Users group has the rights to create personal sites;

8. To verify this log in to the Portal with an account that is a member of the SharePoint MySite Users group. You will see the link to the My Site in the top right corner of the standard SharePoint site template;

9. Now log in with a user who is not a member and you will notice that the My Site link no longer appears;
Using this approach you can safely deploy My Sites functionality across and enterprise in a controlled fashion. This will allow you to ensure quota’s, content database, site deletion e.t.c are provisioned as per the requirements (governance) of your organisation.