Oh，when I was in the high school，I had a contemporary poetry book of 汪国真. It was so boring，that I just took a quick look then I threw it away. I don't think there is any rule for contemporary poetry. Actually rhyme was common for ancient poetry，but not all. For example，before Dynasty Tang，poetry had free style. And opposite to 格律诗，绝句 is much free. Just write something from your heart,:D

Hmm,in fact there're few rules in contemporary Chinese poetry,everyone can wright one,and call it a poem,the style,rhythm are required no lomger. Frankly speaking,contemporary Chinese poetry has little achievement in Chinese literature,the true value of Chinese poetry is Ancient Chinese poems,李白and杜甫 were great poets,they just like Vergilius and Horatius,if you like Chinese poems,you must to learn Ancient Chinese(the relationship between it and Mandarin is just like the one between Italian and Latin),I can promise it is the most beautiful language on this planet,and poems written in Ancient Chinese can not be described.If one day you've mastered Mandarin,and you want to learn Ancient Chinese,I would be very glad to help you with it.It's graceful and gallant.

I think you are right. Strict "rules" such as rhythm and amount of characters per line are for old types Chinese poetry but not for the contemporary. But how to define "rules"? Surely there are rules for the contemporay which I think the important things should include beautiful and/or impressive imago, words, also rhythm, though I'm not good at this.