Building on the script and code posted by ScriptyGoddess, I've made some improvements to the code for expanding/collapsing extended entry text inline:
1. Corrected invalid HTML/XHTML in template code.
2. Corrected a design bug that caused the "read more" link to change from an inline element to a block-level element when "read more" then "hide more" is clicked.
3. Mouse wheel will now scroll page after clicking "read more" link without having to click in page first. (Mozilla Firebird known to be affected by this.)
4. Browser jumps back to "read more" link rather than beginning of post when "hide more" link is clicked.
5. Used meaningful variable and div id names.
6. Applied line formatting to script and code to make it easier to read.
The new javascript and template code, along with documentation of the above changes and the reasons they were made, can be seen on my weblog.