I haven't seen the search results user interface change a lot in the past few years and I don't expect any significant changes in coming years. Jakob Nielsen talks about what search results interface would look like in 2010 during a recent interview. I don't like to predict what will happen in 2010 but I do like to spot the trend and identify the opportunities to improve user experience in general and help improve search semantics. I firmly believe that the search results relevancy is likely to get better and better and we will certainly see more heuristics and machine learning to personalize results based on user's needs and importantly to understand the user's intentions in that moment. The search engine improvements are likely to shift from pure indexing science to better understand the search criteria to achieve relevant search results and there are plenty of opportunities in this area. The “Did you mean this?” correction is just the beginning. This is an area where psycholinguistics can contribute improve the search relevancy. Having said that, I do believe that there is plenty of room to improve the search/results interface and interaction model. Companies like ask.com are gearing their efforts in this direction. Semantic search engines haven't been that successful so far but this is also an area for an improvement in the overall search world.
The interview also brings up the fact that people are generally lazy, but I believe that given the right incentive people might be willing to express themselves better. Spelling and grammar correction is a good example. Though an overly enthusiastic interface asking a lot of information from a user is less likely to succeed. Jakob also talks about perceptual psychology and the ability of showing the images that users are expected to see and actually like and how this approach could turn into banner blindness. The multimedia search results are a big issue going forward as we see more and more user generated multimedia content. A picture is worth a thousand words and a video is worth a million. The images are easy to look at and to comprehend than the pure text but there are challenges on how to select the right images and the same is true with the videos. The video search is an interesting problem and there are many different evolving techniques such as meta information and audio scanning. We will see a lot of progress in this direction.