Sometimes, you need to ask the source for the explanation. And I did. Working in the industry, it's not all that difficult to talk to pros that shoot with Leicas as well as Leica reps and techs that do sell Leica products.
The Panasonic Leicas (25mm, 45mm and the new 42.5mm) are actually built to Panasonic's standards using Leica's past technologies. If you are expecting that Panasonic versions as to be the latest, except maybe not the Noct, then they are not.
This practice is very common, not only for Leica but for Zeiss, Nikon, Canon and all the other makers when they want to reduce costs.
One of the challenges of making affordable products from a premium brand is labour. Cost of labour, training and education are very expensive especially in developed countries like USA and in Europe. In order to bring affordable premium products, some technology transfers must be performed. But when you transfer technology to a low-cost producer like Asia for instance, you can not avoid your technology from being copied. We see this too often with accessories, where we can buy copies cheaper than OEM products. Bearing that in mind, companies usually transfer dated technology to Asia or any other countries where labour is cheap while keeping their latest technology in house. Nikon and Canon making their top of the line cameras in Japan and Leica making their top lenses and cameras in Europe or in Canada at one point in time I believe and license the rest to low cost makers.
This has an effect of building product loyalty at the very bottom in the hopes of people who like these low-end Leicas to migrate to the higher end models. This is also how Canon and Nikon are doing with their point and shoots as well as their APS and DX systems -- migrate them eventually to full frame and expensive glass.
So to address some people's concerns. Yes, these are real Leica technology inspired lenses, but they are not the latest and greatest. If you want to buy the latest generation lens, go with the Olympus 25mm. If you want to buy the feel and look of a Leica, or perhaps it is or it is not, then go with the Panasonic. Either lenses will perform well for your needs.