After temporarily suspending app publishing to its Windows Phone Marketplace a few days ago, Microsoft has released a fix and has resumed publishing new apps. It did point out, however, that it's going to take a couple of days for the fix to "fully deploy" and for newly-published apps -- the ones that caused the errors that led to Microsoft's decision to suspend publishing -- to reappear in the Marketplace.
The problem was initially caused by the rollout of the new Windows Phone Dev Center, which has a different backend infrastructure. This caused issues with the new digital certificates of the apps, leading users to encounter an error when trying to install or update certain new apps. As such, Microsoft put app publishing to the Marketplace on hold a few days ago on August 14.
During the publishing hold, Microsoft recommended that users not uninstall any of their apps after encountering errors, since they most likely would not be able to reinstall them until the company deployed its fix. But now that Microsoft has fixed the digital certificate problem, publishing will resume as normal, and once the fix is fully deployed, users will be free to remove or install their apps as they see fit. The company has also reassured developers that had apps in the process of being published that there is no need for them to take any action, as certification and publishing workflow will resume as normal.