I’m using Firefox 3.5 at home and its great. It adds HTML5 support so it should work with PubCrawler. However, whilst the geolocation functionality works well the local storage does not, so crawls cannot be saved. This is due to the local storage support being of a different type to the WebKit browsers like Safari in iPhone OS 3.x. The Google Gears Add-on is not supported by Firefox 3.5 yet so that’s not an option either. PubCrawler is primarily a mobile web app so this is not high on my list to fix.