Microsoft just signed off on the RTM (Release To Manufacturing) build of their latest Windows Phone OS 7.5, codenamed “Mango”, less than 24 hours ago. Cliff Simpkins, Senior Product Manager on the Windows Phone team, commented on the official blog post that they’re “working to get developers an updated build soon”, and asked everyone to stay tuned to the Windows Phone Developer blog. He later tweeted the following:

[blackbirdpie url=https://twitter.com/#!/cliffsimpkins/status/95975179691376641]

If we’re not reading too much into this, it means that news about an updated build of Windows Phone “Mango” for developers should be coming within a day or so. In fact, this view is supported by another tweet from @wpdevpodcast which hints that Microsoft may be releasing Build 7712 of their Windows Phone OS 7.5 tomorrow:

[blackbirdpie url=http://twitter.com/#!/wpdevpodcast/status/96102295401545728]

Looking at the build numbers, Microsoft recently released Build 7661 to developers just about a month ago. According to WPCentral, the build number on the recent Nokia Sea Ray video leak is Build 7710, first believed to be the RTM version. Then it was suggested (via WPCentral again) that the RTM build that was signed off today was Build 7720. This means that if wpdevpodcast was right, the build developers will be receiving tomorrow will be “close enough” to the RTM build, but not quite the officially signed off version given to OEMs and carriers today.

Regardless, do check the official Windows Phone Developer blog in the next 24 hours to check if we’ll be getting an updated developer build soon. Stay tuned!