Today, Microsoft is reminding its Windows Phone users to update to Windows Phone 7.5. Microsoft said that users might soon need Windows Phone 7.5 in order to update, download, and buy apps from its Marketplace. “We’re now doing the final work needed to turn on this new requirement, so I thought it would be a good time for another friendly reminder,” Microsoft said. If you can still remember last month, we wrote to you about Microsoft’s decision to remove Windows Phone apps from Zune. Apparently Microsoft will push through with its plan to ensure continued Marketplace access. Microsoft made it clear today saying that the new requirement is tied to a larger Marketplace improvement effort. Once these changes are deployed, the only phones that have been upgraded to Windows Phone 7.5 will be able to use the Marketplace. Microsoft added that it will be posting one last reminder before the changes will go live. So, if you find the need to update, you can the instructions via Microsoft’s official website for Windows Phone.