This is an ecosystem:
You see an ad on TV, there's a new {Nokia,Apple,HTC,Samsung,*} phone. Cool beans. Smooth UI, 8-core processor and 9000 TBs of DDR3-2100(LV) RAM.
You go to the $VENDOR store and buy it. Nice {Maemo,MeeGo,iOS,Android,BB+QNX,WebOS,LiMo,WP} on it. Runs smooth, as it damn well should be.
Fast forward a few days later, you're on a road trip. You use the built-in {Nokia Maps/NAVTEQ (which IIRC everyone else uses, it's all the same ****),Google Maps,Bing Maps} .
While you're at a rest stop, you get bored and fire up the {3G,4G,WiFi} to get an app. You visit {Nokia Store,WinMo Marketplace,Apple App Store,Droid Market} to download, Happy Slugs and fling slugs at cats.
You then see a pig on a burning platform and say, hey, that's cool, take a picture and share it via {iCloud,Nokia Services,Windows Live,Google Services} .
Okay, now you're traveling on the road again. There's no FM radio signal. So you get some music that you legally purchased off {iCloud,Nokia Services,Windows Live,Google Services}.

That's what an ecosystem is. If the device makers had their way, they'd lock you to one service and one service only. Imagine that described ecosystem with hardware-enforced secure content paths, mandatory cryptography, mandatory access controls, and user/system separation. This can easily be implemented in Android, iOS and non-Android Linux (via the different security frameworks) and on WP7, it's pretty strongly implemented already.

However, that's on a consumer device, which us geeks don't like. We want THE open device, one that has as many open drivers as possible, we want to literally Install Gentoo on our phones. We want to bring around the desktop experience wherever we go. Us geeks NEED to hack up consumer devices to suit our needs. That's why I bought a N900 in 2011, instead of buying much more powerful, advanced and cutting-edge Android phones. I wanted a device that gives me a desktop-level multitasking experience, compatibility with a lot of desktop apps with no matching Mobile replacement, and because using Linux is fun. There's a reason why so many people on TMO still love the N900, even if it bricks itself, has the worst possible partitioning scheme for a desktop-like system, has terrible performance mostly due to the eMMC plus a measly 256 MB RAM and a ridiculous 768 MB SWAP (!).