If someone of you have in his hands the last number of Microsoft's Architecture Journal (number 7), on page 19 there's a sentence that describes exactly one of the most important topic of nowadays IT infrastructures: "one of the greatest challenges facing the architect today is the integration of applications".
This is extremely true and I recommend to read the article entirely because it's extremely interesting. Application's integration is one of the most important field that an architect today has to understand and I'm sure that if you're involved on developing enterprise architectures, this is always a mountain that you've to climb.
This is an aspect where an architect can place his sign... 