The CPSC has issued a warning to use caution when using slings with babies of under 4 months. The warning has some good safety tips BUT, the news reports, both written and in television are providing misinformation. Some are reporting that the CPSC warned NOT to use slings with babies under 4 months of age. This is not correct.
Some slings are never safe (bag slings, two different good links on the subject) but most are as long as you use them correctly and make sure you use proper positioning and sling safety. Here is a little handout on babywearing 101.
If you ever want a baby carrier and don't know what to buy, try me! I've bought and made many over the years. I carried John until he was over two (not all the time, but it did still come in handy and can still be very comfy, you just have to step outside the bjorn world). Paul gets carried daily, mostly on my back, he can see everything going on and I can get things done instead of him whining when I am out of eyesight. If you want to buy one, I'd recommend a few stores: http://www.slingsilove.com/, http://www.attachedtobaby.com/, http://sleepingbaby.net/. Also if you are handy with a sewing machine, try sewing your own (with quality thread, fabric, and sewing).
Have fun being close to your baby! And just for fun, here is an old picture of John in a Kozy mei tai (a brand I highly recommend!).