I studied abroad spring semester of my junior year. I emailed profs while I was abroad and asked them for rec letters. I gave them a little update about what I was doing abroad and whenever I was in the city, and had access to email, I asked them. I actually had my roommates print out my transcripts, CV and other stuff to give to them. It all worked out well and my letters were in June.
One thing that may pose a problem if you study abroad in the spring is getting your personal statement ready and apps turned in. I took the MCAT this past August and worked and had no time to work on aps. I got mine in Aug 31st. which is fine, but all my interviews are really late. This really hasn't had a detrimental effect, but it's nicer to have confirmation that you are in to schools early on.