Save yourself the $10 a month, there are several places that will do this for free, they will all utilize the RSS feed of your journal.
RSS is a pretty incredible tool, it's like friends list for the entire internet, you might know that your journal has one, just add /data/rss to the end of your livejournal url.
Mine is
http://livejamie.livejournal.com/data/rss Now you can take this URL and go to several different places to get updates when I update!
Several places that will send Text Alerts for Free to your Cell (Text Message Rates Apply of Course)
1) Rasasa
http://rasasa.com/ 2) ZapTXT
http://zaptxt.com/ 3) Yahoo! Mobile Alerts
http://alerts.yahoo.com/main.php?view=blogs 4) Zingku
http://zingku.com/