Well, I don't know the etiquette for this, but yes, I'd feel odd querying about a job that I have no intention of taking. That'd be like asking a real estae agent for a showing but knowing that you won't buy.
If those positions interest you, I'd instad do a initial contact saying "I saw this listing on X and the job description sounds very exciting because blah blah blah about my background and expertise. However, I will not be graduating till next summer. If you come across similar job listings in the future near that time frame, I would greatly appreciate it if you can think of me and drop me a line again. Thank you."