From http://dev.chromium.org/developers/design-documents/user-scripts

• Chromium does not support @require, @resource, unsafeWindow, GM_registerMenuCommand, GM_setValue, or GM_getValue
• GM_xmlhttpRequest is same-origin only

My script uses 4 out of these 6 features, and also cross-domain GM_xmlhttpRequest (the comments are actually loaded from a PHP script hosted elsewhere, because LW doesn't seem to provide a way to grab 400 comments at once), so it's going to have to stay Firefox-only for the time being.

Oh, in case anyone developing LW is reading this, I release my script into the public domain, so feel free to incorporate the features into LW itself.