<p>I've got a <a href="http://notebooks.readerville.com/" rel="noreferrer">site</a> that provides blog-friendly widgets via JavaScript. These work fine in most circumstances, including self-hosted Wordpress blogs. With blogs hosted at Wordpress.com, however, JavaScript isn't allowed in sidebar text modules. Has anyone seen a workaround for this limitation?</p>

you could always petition wp to add your widget to their 'approved' list, but who knows how long that would take. you're talking about a way to circumvent the rules they have in place about posting arbitrary script. myspace javascript exploits in particular have increased awareness of the possibility of such workarounds, so you might have a tough time getting around the restrictions - however, here's a classic ones to try:
put the javascript in a weird place, like anywhere that executes a URL. for instance:
```
```
<div style="background:url('javascript:alert(this);');" />
```
```
sometimes the word 'javascript' gets cut out, but occasionally you can sneak it through as java\nscript, or something similar.
sometimes quotes get stripped out - try String.fromCharCode(34) to get around that. Also, in general, using eval("codepart1" + "codepart2") to get around restricted words or characters.
sneaking in javascript is a tricky business, mostly utilizing unorthodox (possibly un-documented) browser behavior in order to execute arbitrary javascript on a page. Welcome to hacking.