One big area that developers had a gripe about in the Marketplace was the seemingly arbitrary limit of only five free apps could be submitted to the Marketplace at no cost. Microsoft had set the number, meaning you could submit five free apps to the Marketplace without paying the $20 app submission charge.

After hearing developer feedback on this topic, Microsoft has finally altered this requirement, bumping the number of free app submissions from five to a nice cozy one-hundred. That number will surely give devs ample room to work on releasing apps, without that cost fear over their heads.

The goal was originally meant to prevent developers from pumping out a ton of free, but low quality apps to the Marketplace i.e. clone apps with slightly varying titles, etc. So the intention was good, but the problem was this: free, ad supported apps ended up bringing in more revenue for developers than some paid versions. Take someone like game-developer Elbert Perez (Impossible Shoota, others) who made all six (and counting) of his games for free/ad supported--he'd have to pay $20 for each submission, including if it failed the resubmission.

So once again, good on you Microsoft.

Source: Windows Phone Marketplace Developer Newsletter; Thanks, Justin Angel, for pointing this out