When Microsoft first released the list of what'll get an app blocked from Windows Marketplace for Mobile, some of the reasons weren't entirely clear. Now, we're happy to say, a number of them have been answered.

Microsoft's Loke Uei spoke on the Winmo World podcast (which features the guys from wmpoweruser, Unwired View and pda.pl) and cleared up some of our questions.

• No VOIP apps using a carrier's data. (WiFi is just fine. But no Skype over 3G. Sorry, folks. Saw that one coming.)
• No apps with an OTA download of over 10MB. (That's for the initial app download. So, no 800MB Myst games. Once the app's on your phone, it can suck in as much data as you want. Er, so long as it's not VOIP.)
• No apps that change the default browser, search client, or media player on the device. (Admittedly, they need to define this a little better, but they're working on it, and apps like Opera, Skyfire, Kinoma and the like should be OK.)

There's also a lot of talk about fragmenting the Windows Mobile application ecosystem with these rules, which will keep a number of apps out of the Marketplace. Our take on that:

The Windows Mobile application ecosystem already is fragmented. Yes, there are software houses that sell their apps under one roof, and there are sites such as Handango (and the WMExperts Software Store) that sell a number of apps. But it's safe to say Microsoft will be bring a weight and legitimacy to to the process that has been lacking for the average consumer.

The Marketplace should help bring the ecosystem together. Will it reach the level of integration of Apple's App Store? Certainly not at first. And maybe not ever. (And that's not necessarily a bad thing.) But suffice to say the Marketplace is still one of the larger developements for Windows Mobile to come out of the past couple of years.