I find the prevailing view that Linked Power reduces the manifestation time of the second power to be a very generous reading of the feat. After all, there is this:
In light of the bolded text in the spoiler, a DM could say that, yeah, a power that takes more than 1 standard action to manifest "goes off" in the next round, but it still takes the full duration in its individual description before the effect comes into being. In other words, the timer starts running down, but you still have to wait the full minute or whatever until you actually see something happen.
Another DM might say that you simply can't use the feat with powers that take more than 1 standard action or 1 full round action to manifest.
The bottom line is that a textual ambiguity exists. Not all DMs are going to be generous and interpret such ambiguities to the players' advantage.