Since the release of the iPhone 4 and its brilliant Retina Display, the amount of available themes for jailbreakers has been greatly diminished. First, the jailbreak for iOS 4 took some time, and once it happened it seemed no one was quick to convert their existing themes to match the stunning Retina Display quality. A few have started to crop up, now that the jailbreak for iPhone 4 seems permanent.

Themes seemed like a lot of fun when I first jailbroke my iPhone, but they quickly lost their novelty as they were often battery hogs and well, just plain tacky. But sometimes I like to change it up, and now I know the simpler the theme, the better. (Hey, kind of like Apple’s design… imagine that!) Enter the Glasklart HD theme, designed especially for iPhone 4.

This theme gives your iPhone that black-and-white-film feel, with all the icons shades of gray, many of which are simplified version of the native app icon. The sheer number of apps always makes it difficult for custom themes to have every one of your icons converted, but Glasklart seems to have far more than any other theme I’ve tried thus far.

I also like that the icons aren’t vastly different than the native ones as it makes it easier to adjust to the new look. In addition, Glasklart HD has its own rendering of the Liveclock icon, one of my favorite tweaks.

The SMS app is also designed to match the theme, using the dark/light shades of gray to alternate the bubbles. The theme even has matching badges, as well as the X badge in the multi-tasking view. (Inexplicably, the minus sign badges are red).

There’s also some lockscreen/slider tweaks the theme provides. Most of these options can be turned off and on in Winterboard, so you can mix and match the features of the theme you like the most. Additionally, there are some other black/white tweaks available in Cydia, such as the White/Black Signal Bars that matches perfectly with the Glasklart HD theme.

The font is not part of the theme. I downloaded and installed the Surface Font separately (learn how to do that here), but I think the uber-skinny font fits well with the minimalist theme.

The Glasklart HD theme is available for free in Cydia, and is authored by Max Rudberg. Let us know what you think of it in the comments if you try it out, or if you think there’s a better theme out there for the iPhone 4 that we should give a spin.