Today I went to the RStudio site to post a feature request. I noticed up in the top navigation a link called "Shiny". I like things that are shiny. It turns out Shiny is a new package the RStudio team has developed for easily making reactive web applications from R code.
One of the tools I built at my current job is a web application that uses R as the server side analysis engine with A LOT of HMTL/CSS and AJAX tomfoolery in the browser to make things responsive a pretty.
From the looks of it, the shiny new Shiny package will significantly reduce the UI development time. In fact, it appears to make web UI development more like UI development in desktop python apps using [insert your favorite toolkit here] (note: so far I mostly have experience with wx).
Ever since I started using R (back in 2007) I often lamented the lack of a way to create easy to use GUIs that could encapsulate complex analysis scripts for non-R users. In MATLAB, this is done using GUIDE or low level uicontrol() functions. In 2009, RGG looked promising, and I also found SciViews-R, but I never really had/invested the time to look deeper into either of these tools. Besides, doing things from the comfort of a web browser is all the rage these days (and certainly makes deploying app updates easier).
I'm looking forward to testing this out!