|This dialog lets you add collaborators to your custom map|
The answer is yes - provided the people in question have a Google account.
Here's how you go about it. First, open the map in My Places in the usual way. Then click the Collaborate link, which is near the top-left corner of the left-hand panel. This will open a dialog like the one in the screen shot.
To invite specific people to edit your map, type their email addresses in the "Invite people as collaborators" box. Use commas to separate the addresses. In each case, the address must be the one the collaborator uses to sign into their Google account (this is not necessarily their Gmail address.)
If you wish to add your own text to the invitation, type it in the "Add your message" box.
When done, click "Send invitations". Don’t worry if nothing appears to happen. You will eventually see a message telling you that the invitations have been sent, but this might take a few minutes to appear. Your collaborators will then receive an email (from your own email address) inviting them to view and edit the map.
That's basically all you need to do. Your collaborators can simply click on the link contained in the email. They will see the map in My Places, complete with an Edit button, ready for them to start work.
You also have a couple of other options. If you wish, you may give your collaborators the ability to invite other people in turn to edit the map. To do that, check the appropriate box under "Advanced Permissions".
You can also allow anyone to edit the map (anyone in the world who has a Google account). I can't think of any reason for doing that, but if that's what you want, again check the relevant box under "Advanced Permissions". In this case, of course, no email invitations will be sent. But anyone who knows the map's URL will now also see the Edit button when they view the map.
Finally, you can remove any or all of your collaborators at any time. Just click the Collaborate link again, then click the Remove link against the addresses of the people in question.