I am planning to realize apps to be used from Surface Win8 new tablet.
Will it be necessary to pass from the new Windows App Store (as it happens for iOS) or will I be able to distribute the .exe without passing from Microsoft?
As far as I aquired information. There are assumptions that the standard Surface have no Desktop mode. That means the pad will be purely comparable with Android and iOS. The Pro version will instead also be delivered with desktop mode also. In normal terms "full Windows 8".
If that's the case, you can install and run Metro specific applications on Standard, or better described "Applications developed under WinRT". But with Pro version, also windows desktop applications like classic Office and such.
[UPDATE]
Based on a few QA from Microsoft, they are going to make differences in Windows 8 versions. They are going to offer distribution of apps outside the store. This is an extremely important point in example to business line use, and intranet purpose. Though, they are about to make this available to an Enterprise version of Windows 8.
"..Only the Enterprise version of Windows 8 will have the capability to 'Side Load' Apps. Side loading bypasses the Windows Store to install custom Enterprise Apps within an organization.."
I feel the answer is a little of "Yes, you are able to distribute the apps outside the store" and "No, for public or world wide use, you have to go through the Windows Store". As a distributor, it appears to be a work-around. Though, the recipients of this "side-loaded app" have to be aware of that work-around. This is a citate from Microsoft Developer page,
Preparing other PCs Some business users might not use a PC that supports enterprise sideloading. Common reasons for this are that the edition of Windows that their enterprise uses doesn’t support this, or the IT admins do not manage the PC. This scenario is becoming increasingly common with the growing trend of personal devices used for work.
To enable sideloading of a Metro style app onto a PC: Set Group Policy for “Allow all trusted apps to install”. If you cannot use Group Policy, then you can set this through the following setting: HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\Appx\AllowAllTrustedApps = 1 Verify that the app is signed by a CA that is trusted on the target machines Activate a special product key by using a script on the target machine to enable sideloading. We'll go into more detail about how the IT admin will acquire the product keys in an upcoming blog post. The product key only needs to be install and activated once on the PC.
For Business purpose, it appears to be a kind of package distribution where you can select which enterprise users should be eligable for which Windows 8 - metro - applications.