A small information about the future Sony Alpha 77: If we know that it will include an electronic viewfinder (EVF) since the revelations from the Sony marketing, we were still lacking some technical details.
I just learned that this electronic viewfinder should be based on an OLED display with the exceptional contrast of at least 10000:1 and a wide color gamut covering more than 75% of the NTSC 1931 CIE standard. Its resolution should be over 1.5 mega-pixels and possibly more than 2 mega-pixels, with very small inter-pixel spaces.
This is -indeed- susceptible to produce a much better quality for the Sony SLT-A77 than on the SLT-A33 and SLT-A55 presented by Sony in 2010 in the Alpha range.
I could not find any Sony data about the exact features of the A33/A55 viewfinder LCD. However, there are a few things that can be observed and a few state-of-the-art technological elements to add in order to relativize the exact impact of this possible leak.
Good desktop LCD displays (and good TV sets) are usually in the 100% – 130% range of the NTSC standard (beyond NTSC, most use the wider AdobeRGB gamut reference), but the smaller LCDs tend to navigate in 50-55% waters.
Also note that 100% of the NTSC (which is an old standard from the 50’s) is still quite insufficient for most photo applications (video tends to be more tolerant). It make this A77 proposition of a VF as a significant progress, but this stays in low quality levels.
Small LCD displays (not the video-projection LCD panels, but those found in the back of our photo cameras and apparently what has been used by Sony on the A33/A55) have contrast ratios around 150:1, sometimes but not often much better. Here, the improvement should be very perceptible.
As for the resolution, the A33/A55 have a 1.5MP EVF. So, there will be no progress or a very small one.