Also, the mobile version uses the same protocol as all of the other products (such as gmail). You can take our Open Source library (http://code.google.com/p/libjingle) and use it to make an app that calls the mobile version, just like you can for the other products.
The funny thing is that if you actually made Google Talk good, it could easily be the #1 chat application. XMPP Transports are far and away the best solution for managing presence on multiple protocols, if Google provided reliable transports for AIM, Live, FB etc then, combined with the (absolutely awesome) centralised chat history feature you could definitely win users over (I have set up transports on my Google account anyway using Gajim and hot-chilli.net, and it's brilliant). However, GTalk doesn't support XEP-0030 or XEP-0144 which make the process a lot nicer.
Lastly, the desktop and web clients are both a complete joke. The web client can become disconnected without "realising" so your messages go into a black hole, and the desktop client steals focus which is an instant uninstall for me and for many other users.
Perhaps I'm being naive, but the problem of sending a message to a person and making sure they definitely get that message does not seem to be difficult. It works with very high reliability through GMail, for example, or when posting a comment on Hacker News... but for some reason as soon as we are in the domain of "IM" then reliability becomes a serious issue (except with Skype, which is the only IM client that gets this right (and that is the ONLY thing that Skype gets right)).
TLDR: Please make Google Talk good, because it really has huge potential and already has some massive advantages against the competition. Right now though, it has so many huge problems that frankly I think adding video message support is like polishing the brass on the Titanic.