I recently started in a new job where we use Common Lisp as the programming language for all the core work. The company is SISCOG and it sells software for planning the Human Resources of train companies. In SISCOG they provided an intense 3 weeks course on Common Lisp, but, due to legal and project schedule constraints in my previous work at Nokia Siemens Networks, I only participated in the last day of the course. So, now, I'm learning on the job and by my own in my free time. I'm reading Practical Common Lisp, using Lisp in a box, and Franz's Allegro CL and it is going alright.
Because I was used to developing in Python I'm not finding so hard to get used to Common Lisp, even with the very different syntax. The main thing is being used to working in a dynamic language. Ah, and the Lisp prompt – or REPL in Lisp terms – is very good.
The hard thing is to get used to the libraries and toolset to the point where I'm so productive as I was in my previous environment (Java and Eclipse). Now I'm using emacs as the editor and Allegro/emacs as the IDE. Besides the GUI framework that comes with Allegro, everything is internal to SISCOG, so, I have a lot to learn. And from my previous experience, the best way to do it effectivelly is by participation in an open source project. There you normally get into contact to the best software engineering practices and best user / developers relationship that is possible. So, I already looked around and my two candidates for now are: