Ronen has posted a great little how to for getting a Hebrew font on your BB. You can also do this by installing a multilingual OS on your device but hunting for the right one is a pain.
Smartmouth let me know that created a download page where you can easily find the right files to install Hebrew fonts on your device. The best part is that you do not need to reinstall your OS to get Hebrew fonts since this installs like an application. Smartmouth set it up that you can even add some of the read only fonts OTA but if you want to be able to write with the fonts you will need to do this using the desktop install files on the same page.
Check it out at www.cheservices.com/blackberry/
Right now this method supports:
OTA Hebrew Read Only & Menus:
o BlackBerry Storm, 83XX Curve Series, 88XX Series, 82XX Pearl Flip Series, Bold 90XX Series, & 7290
Desktop Manager Hebrew Read & Write support:
o BlackBerry 8900 Curve, 83XX Curve Series, 88XX Series, 82XX Pearl Flip Series, Bold 90XX Series