Development releases of Telegram on desktop and Android show that users will be able to theme their apps through an easy-to-use menu. Technically, Telegram on desktop has had theme support ever since the 1.0 release last month, however, it was not easy to set a custom theme because you either had to code one for yourself or hunt one down in dedicated groups and channels.
The new theme selector in Telegram looks quite powerful, rather than having a marketplace of themes to pick, users can select the colour of each individual component of the messenger. Any themes you make will be accessible in the themes menu so that you can switch between them as you want. The beta also gives you the option of editing an existing theme and of sharing it with contacts.
One other feature was uncovered in the latest beta of Telegram, but it doesn’t appear to exist anywhere outside the underlying code just yet, meaning you can’t use it. It looks as though Telegram will soon include payment functionality. At this early stage, it’s impossible to know how it’ll work, but Telegram could seek to partner up with various financial bodies to incorporate their services into the app. Last month, Telegram's CEO Pavel Durov said that calls will be coming to the app soon.
Source: TGbeta (requires Telegram)