“me.com” is currently a placeholder page hosted by MarkMonitor, a company that specializes in brand-related DNS management. You can see that it’s handled by MarkMonitor by checking the whois information for the domain. Apple uses MarkMonitor for most of its domains, including “apple.com”, and it’s where they’ve previously parked domains for future use.
nslookup -q=soa me.com” in Terminal to see this information.
“mobileme.com” is parked at MarkMonitor, too, but “me.com” is a bit punchier, no?