If you're interested in getting a .MX (Mexico) domain, you need to get started in the by March 1st 2009. The rules are changing: for the past few years, you could only get a .com.mx domain, but now you can get YOURDOMAIN.mx.
To get an .mx domain, you need to own a .com.mx domain by March 1st (2009) -- better get hopping. The .com.mx domain can then be "converted" to a .mx domain in May. However, you'll be competing with owners of YOURDOMAIN.edu.mx, YOURDOMAIN.org.mx, etc. Oldest domain registration wins.
The .MX domains are pricey too: $99 for one year.
Happy Domain Hunting!