Despite custom ROMs based on the software already being available if you look in the right places, there is still a lot of mystery surrounding exactly what the Windows Phone 7.8 update will provide. The update's only officially confirmed feature is the new Start screen, and that is all Microsoft has told us about 7.8.
However during this week's Verge Mobile Show, co-host and the site's senior mobile editor Chris Ziegler revealed some of the gossip he's heard in the last few weeks regarding the relationship between Windows Phone 8 and the 7.8 update. At the 39:31 mark into the show, Ziegler says a "very reliable source" claimed Microsoft made a last minute decision to port exclusive features originally only meant for WP8 back into the 7.8 update.
Ziegler goes on to say that this may be the reason as to why the shipping dates for both have seemingly been delayed. Furthermore, his co-worker and deeply-connected Microsoft detective Tom Warren had supposedly backed up that claim. You can watch Ziegler mention this rumor in the video posted after the break (should start automatically at 39:31).
The Verge has had several Windows Phone-related leaks this year that have turned out true, so there is a decent chance this rumor is legit. However, as far as we know today Windows Phone 7.8 only officially includes the new Start screen, and that's all you should be getting your hopes up for until we learn more.
Update: As pointed out to me by another podcast host, Andrew from Glance and Go Radio, it was just three weeks ago that Microsoft began accepting feature requests for the 7.8 update. That lends some credence to this rumor, though Microsoft did end up backing away from the feature requests. Take that as you will.
Source: The Verge