RoaringApps is maintaining a wiki listing hundreds of Mac applications and what is currently known about their compatibility with Lion. Anyone can add entries to the list or modify existing information. Although the information is preliminary (and not all of it comes from official sources), it can serve as a useful guide for people preparing their disks for an upgrade to Lion next month.follow link
Beware Country-Specific iTunes Stores
If you buy an iPhone, iPod touch, or iPad, and you happen to be a user of the iTunes Store in more than one country, take note which country's store you're viewing in iTunes when you plug in the device for the first time. This will be the country the device will register with, and you will be forever barred from purchasing or even updating free apps from anywhere else. The only way out is to delete everything on the device and do a full restore.
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Lion Application Compatibility Wiki