I just upgraded my iPad to iOS 5 — wow!  There’s lots of stuff in there.

What’s most interesting are features that Apple’s pulled in from their app ecosystem. This is great for users (Apple gets to cherry-pick the best ideas).  But it’s risky for app developers who can see their hard work turn into free features, and then deeply integrated in a way that only Apple can do.

I’m making a running list of who’s impacted:

• Instapaper.  Safari how has a “Read later” feature, and a nice “reader” mode that defeatures Web pages, showing only the content.

• Web advertisers.  The Reader mode presents text content beautifully, free of ads.  I was wondering when we’d see a main-stream browser with an ad stripper.

• Twitter.  Deep iOS integration pushes Twitter further into utility space.  More tweets will flow through Apple-controlled UIs, moving Twitter closer to being just a tweet packet router.

• Wunderlist (and all the other task managers).  Apple can do a TODO list like no other, with location based reminders and voice input (presumably coming with Siri).

• Wireless carriers.  iMessage (Apple’s response in part to BlackBerry Messenger) is an end-run around text messaging.  It looks like it can work on email handles as well as phone numbers, so kids can start using it with their iPods.

Long term, I see threats to:  

• Dropbox (and all other file sharing companies).  File sharing is begging to be an OS feature, and iCloud (and Amazon’s Cloud Drive) are moving in that direction.

• Laptops.  You can now (finally!) activate and use an iPad without a PC, making it a compelling Internet device for users with no other computer.