As it stands right now, overlay code does exist to be able to display the player and other things at the same time. That still leaves two problems. One is launching the programs. Right now, it would have to be done either before or after the player is run, or a wrapper would need to be built like the irhack to intercept a key combo to then pop up an apps menu. The second problem is the unfriendly nature of the player. It sits at a very high priority (for a good reason), so this can cause problems to programs at lower niceness levels. Plus, even if a program does run at the same level as the player, slowdowns will occur as seen by pressing the tweak order button rapidly. (Something that has been confirmed as fixed in 2.0 by setting non music pumping threads to lower priorities instead of the same).

It looks like a long way off still before anything emerges to allow easy empeg and 3rd party integration. It has come a long ways though from the "poke at it with a stick" Mark 1 launch days.