Absolutely, yes. At the time, I was right in the middle of our University's site redesign, and literally learning CSS one rule at a time as I was going along. I actually never intended to enter any of my designs to the Garden; even though it was still in its infancy, it already featured such high quality entries that I felt my meagre attempts would be quite inadequate. As CSS was fast becoming the most popular topic in the web design area over at Sitepoint's forum (were I was a moderator at the time), we decided to run our own 'garden-like' competition. I was involved in the contest's organization, and developed two example designs: the default Sitepoint style, and the slightly more elaborate 'Gothic'.
Imagine my surprise when, out of the blue, Dave Shea emailed me to ask if I'd like to rework 'Gothic' as an entry to the Zen Garden. It was this initial vote of confidence that pretty much took the 'fear' of the Garden from me and spurred me on to explore a variety of new techniques and styles, pushing my knowledge of CSS further than the constraints and boundaries of my large Salford redesign would have allowed.
Certainly working on 'door to my garden' (which seems to be my most successful entry, even managing an appearance in Dave and Molly's book 'The Zen of CSS Design' - see the sample chapter at creativepro.com) has provided me with a very strong grounding on the various issues involving the use of background images and cross browser alternatives, and probably represents my most 'finished' piece of work in terms of striking a good balance between visual design and clean, simple stylesheet usage.
For completeness' sake, it may also be worth mentioning that I have two more entries which unfortunately did not quite make it into the 'official' list: phonephreak in the 'conceptual designs' category, an admittedly unreadable design that mimics a double page spread magazine layout, and an advanced version of 'door to my garden' under 'special effects', which uses some :hover trickery in browsers that support it, yet degrades gracefully in those that don't.