After years or cooperation and little overlap, Google and Apple are regularly encroaching on each other’s turf. The Wall Street Journal in a lead article points out the areas of overlap, summarized in this diagram:

Coopetition Between Apple and Google Grows
For a long time, both companies seem to have followed Abraham’s advice to Lot: “If you go left; I’ll go right; if you turn right, I’ll turn left.”
No longer.
Increasingly, they are at it head to head, as Google finishes its Chrome Operating System, beefs up YouTube, challanges the iPhone with Android, and otherwise seeks to dominate turf long-held by Apple.
Accordind to the Journal article,
More acquisitions could be in the works as Silicon Valley dealmaking heats up overall. As the worst of the recession appears to have passed, tech companies are eager to pick up promising technologies before prices climb.
Google, which has nearly $22 billion in cash, has been particularly active. In addition to AdMob, Google bought display-ad company Teracent Corp. and Internet-phone provider Gizmo5 Technologies Inc. in November. Last week it purchased AppJet Inc., a maker of online collaboration software.
Apple, which has $34 billion in cash, has been exploring buying iPhone-related technologies that it doesn’t yet have, say people familiar with the matter. Its moves are generating particular attention because Apple has made fewer acquisitions than other companies of its size.
To the GoogleGazer, this competition is healthy, and will inure to the benefit of consumers.