On OSX, throw this in your crontab to run every 10 minutes or so and once the http://macromates.com/ page changes from
it's 'Yes, it's almost here...' page it will pull up the site in your default browser. Make sure it's all on one line.
ruby -rnet/http -rmd5 -e "system('open http://macromates.com') unless MD5.new(Net::HTTP.get('www.macromates.com', '/'))
== 'f236ab04b4b0ef41e0d9d6030645cb63'"