As of right now there is intellisense for HTML, CSS and JS. It would be a great addition to have the intellisense for apex in visualforce pages. for example as you type apex: an option list shows to give the available options. Also as you type to should the available attributes for the apex DOM elements. This would help out those who may not know all the available attributes that salesforce offers and saves time when developing without having to wait for the error log on compile.