Marketplace is the only way to get apps on to Windows Phone 7
No sideloading from PCs, no downloading from the web
Not only will Windows Phone 7 Series devices not run Windows Mobile apps; you won't be able to install apps from the web or using the Zune sync software from your PC.
The only way to get apps will be to install them over the air from the Windows Phone Marketplace (and the XAP install files will be automatically deleted from the phone afterwards)
Developers will be able to sign up and unlock their own phones so they can sideload apps they're developing from the PC. The director of product management for Marketplace, Todd Biggs promised more information in May about "other distribution scenarios" including whether enterprises will be able to get apps onto Windows Phone handsets without putting them in the Marketplace.
Testing programme to be offered?
John Bruno from the Marketplace team said they're considering "offering a programme to allow you to beta test your app with a set of invitees so you could get feedback on it". May is also when we'll find out about what Briggs calls "conditional business models" like subscriptions and buying extras within an app; currently apps are either pay-for, free or limited feature trials.
Your Marketplace account will be associated with your Windows Live ID and you can use it for up to five devices; Biggs says users will get access to apps they've bought on all the devices on their account and "if I go sailing and drop my phone in the ocean I can get another phone and I'm able to sign in and get my apps back."
The Marketplace can also delete apps from your device automatically (if they're found to be malicious or break the conditions of the Marketplace).
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Those conditions are transparent and predictable, says Bruno, and the criteria will be public "so you know what to expect".
Parental controls?
Apps can't interfere with the phone functionality (which presumably means no alternative diallers), they have to be "well behaved" and use device resources efficiently. Plus they have to meet Microsoft's content policies globally (as well as any laws in individual countries). Biggs calls the standard "kind of PG13"; the Marketplace won't accept adult content.
There might be parental controls in a future version but Microsoft is looking for content that he calls "acceptable to the broadest audience".
Also on the list of unwanted apps might be alternative browsers. When we asked Larry Lieberman, the senior product manager for the Windows Phone developer experience, he told us "An alternative browser is an interesting question. We think we have a substantially improved browsing experience in this device as one of the core experiences that we're trying to deliver and take responsibility for - there may be policy reasons why we wouldn't do that, but I don't know the answer."
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Liked this? Then check out Hands on: Windows Phone 7 Series review
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Mary (Twitter, Google+, website) started her career at Future Publishing, saw the AOL meltdown first hand the first time around when she ran the AOL UK computing channel, and she's been a freelance tech writer for over a decade. She's used every version of Windows and Office released, and every smartphone too, but she's still looking for the perfect tablet. Yes, she really does have USB earrings.