I think the important thing for people to know is not where the lobby server is located, but how good their ping is to the server.
So instead of attempting to find actual ping, or display the server on a map, I'm proposing that we have a simple 4 bar solution based on IP location of the user that is shown alongside each lobby.
4 bars - location for both user and server is within same region (East Coast NA, West Coast NA, UK, Western Europe, Australia, etc...)
3 bars - location for both user and server spans two adjacent regions (East Coast/West Coast NA, Eastern Europe/Western Europe, Australia/New Zealand)
2 bars - location spans across regions (East Coast NA/UK)
1 bar - location spans further than previous bars (Australia/UK, West Coast/Eastern Europe, etc.)
This is the basic concept. Implementation could be via region detection, or set distances for each tier.