... and also love the LENS BLUR filter.
Up until now it has been frustrating as you can NOT use the LENS BLUR (filter=>blur=>Lens Blur) with a smart object (or, in other words, as a Smart Filter).
I just found out this crazy yet simple solution:
#1: download THIS FILE
http://reinography.com/temp/EnableAllPluginsForSmartFilters.jsx.zip , which is a JavaScript (tested and approved by folks that care).
Unzip it.
#2: For MAC users, go to: APPLICATIONS/ADOBE CS4/SCRIPTING... if you have a JavaScripts folder, great. You may already have this file sitting in there... if not, move the above JavaScript into that folder. If not, you can just put it inside the SCRIPTING folder itself. Just as long as you can find it again for the next step.
#3: Open Photoshop, and go to FILE=>SCRIPTS=>BROWSE, and then go select the above JavaScript file from where you just moved it to.
#4: follow the prompts.
Next thing you know you've got fully non-destructive LENS BLUR ability. And trust me, for blur effects that you want to look like a camera made them, the LENS BLUR blows the Guassian Blur away. Specially when you are using OPACITY to control how much blur is going on. With the SMART FILTER option you can acually PAINT in the amount of blur you want. SWEEEEEEET!
For PC users: I did some digging on our old PC, running CS3, and the script is actually already in there! Here is the path:
The only thing you have to do is follow step #3 above, and you are rocking the Non-Destructive Waves of Smart Object FUN!
(
and a very honest thank-you to CafN8d, who turned me onto Smart Filters a couple years back when we did or Coolaboration BEAVER FUN chop... thanks CfN8dGAL. )
I am, after all, CANADIAN. 
