Google has released six new technologies that were tested in Gmail Labs and will become permanent options in the main product version.

Among the innovations: forgotten-attachment detector, custom label colour in Gmail, vacation auto-responder.

In addition, Google Mail now has search query autocompletion — this option is currently available only to English-speaking Gmail users.

A handy new YouTube preview function converts a YouTube URL into a small inline player. A similar lab project that converts photos and images from Picasa Web Albums and Flickr also exists but is still in testing. The Gmail vacation responder sends an automatic reply to senders when the user is away.

Google was publicly testing around 60 Gmail features but reviewed all projects last Wednesday and decided to drop some. The removed options include: the screen lock that forced 15-minute work breaks; fixed-width font; location in signature (adding the user’s city and country based on IP); random signature that inserted random quotes.