One of the broadest definitions of bioinformatics that I have come across was in Sorin Draghici's book, Data Analysis Tools for DNA MicroArrays.
Def: Bioinformatics is the science of refining biological information into biological knowledge using computers.
Under the heading of bioinformatics is a wide variety of different fields of study with a lot of problems under its umbrella. Some of the primary issues addressed, historically, have been sequence analysis, protein structure prediction and the dynamic modeling of complex biosystems. Other areas of fairly recent research has been in protein-protein interations, protein-DNA interactions, enzymatic and biochemical pathways, population-scale sequence data, large-scale gene expression data and ecological and environmental data.
That's what Draghici has to say about it, anyways. As a newbie, I am discovering all the time new avenues of research and trying to assimilate and categorize all the new information I'm coming across. So far, it looks like my research will begin in the areas of sequence analysis, modeling of biosystems, pathway analysis and analysis of gene expression data.
The first project in which I am involved is simply cross-species comparison of genes that have been identified in one species through expression analysis as having a role in cell wall development. We'll use this information to predict their role in other plants as well.
I'm already having quite a good time at my new job taking care of some techie stuff, more so than I ever had a chance to do in my last profession. I've tweaked a website design to meet the boss' requirements, migrated a database website from one server to another one (learning a good deal about MS SQL Server in the process), identified and solved a particular issue with the Genespring workgroup server.
I'm also utilizing a new software tool on my own server, something called activeCollab, a project management utility. It is an online database of my current projects and activities. Through a fairly easy to use web interface I am able to enter all my projects along their tasks, messages, milestones, etc. I've provided access to my colleagues and my PI to allow them to keep tabs on my progress. Plus, it helps me to make sure that I am staying on task and meeting all my own goals.