Jamie correctly points out that the idea of having the search functionality present at all times without popping up an annoying dialog box predates Firefox, it has been availble on Emacs and XEmacs forever:
Emacs search functionality is also a bit more evolved at this point than Firefox (in an Emacs kind of way). Anyways, I can not wait for more desktop applications to use this model for searches.
Gonzalo has posted some details on the evolution of Mono's performance for WebForms and WebServices here.
Summary: Loading a test that shows a directory listing without any caching enabled has gone from 30 requests per second a year ago to 155 requests per second as of Mono 1.1.7. Check the details on the incremental improvements that got that performance.