One plausible scenario is that you have to upload all your non-iTMS while your iTMS music can be streamed right from the start. Well, that’s at least the minima

One plausible scenario is that you have to upload all your non-iTMS while your iTMS music can be streamed right from the start. Well, that’s at least the minimal required scenario to make this service attractive when compared to Google’s and Amazon’s services. Apple gets extra points if you can immediately stream all the music in your library – no matter its source – if it is also available in the iTMS. (That would, by the way, also save them space and bandwidth and make it possible for them to be pretty competitive.) My guess is that it’s either unlimited or has a pretty high limit. Google’s service is currently capped at 20,000 songs†, Amazon’s free service has space merely for a few thousand songs (5GB or 20GB if you purchase an album from Amazon MP3). Paying $30/year (after buying an album and getting the 20GB bump) gets you altogether 50GB of Amazon Cloud Drive space. That would be my minimum expectation for Apple’s service, too. (I would still be disappointed. 50GB still fit my current music library – but for how long?) A 20,000 song limit (that’s about 160GB assuming 3:30 long 256kBit/s AAC files∆) would be more reasonable and at least be much cheaper than Amazon’s service (if you go with Amazon, 100GB cost you $80, 200GB cost you $180). It’s also possible that those $25 include some or all services that are currently part of MobileMe (iDisk, email, calendar and other syncing, …). †It’s currently free and requires an invitation but might be no more after it is out of beta. Comparisons with Google Music are at this point in time moot. ∆Apple wouldn’t actually need all that space and the associated bandwidth. First of all, not all people have 160GB music collections. Also, all music bought from the iTMS (and maybe all music available on the iTMS depending how the service will work in the end) doesn’t have to be uploaded and only one copy of it has to be saved. I have 20GB of music bought in the iTMS and 20GB of ripped music, I would only need 20GB of space.