Lets say you have a number of channels in the Graph Editor. Select one of them and do SHIFT+H which hides everything but what is selected. Awesome, that's brilliant.
Problem is, if you then select one of the channels that's hidden and do SHIFT+H it just hides everything and doesn't reveal the channel/channels that are selected. This issue doesn't come up in the viewport since you can't select objects that aren't visible. When working with channels it seems very intuitive to the user that this function should show what ever he/her selected and hide everything else.
In short: SHIFT+H in the Graph Editor should reveal channels that are selected and hide those that aren't selected.
Blender 2.72 Gooseberry Branch