Here are some Mexico internet stats:
111,211,789 Mexico Population ('09) (about a third of the US)
27,400,000 Internet users as of Dec/08, 24.6% penetration, per eMarketer. This is getting close to the whole population of Canada.
4,804,282 broadband connections as of Sept./07, per OECD, 4.4% p.r.
Mexico borders the USA, is close to Canada, does lots of trade with both countries, and is swarmed by tourists in fall, winter, spring months.
I think country codes are good investments, and commerce over the net will increase over time like everywhere else.
The .mx landrush is a nice chance to get in on this market at the early stages, if you pick good keywords. The regs will pick up as the price comes down.