Its not ready for new iOS4. I downloaded and it crashed. I did a search and found a beta repo for them and downloaded. Everything seemed fine but I had to resubmit for a new license. It just would not work until then. Last night I realized I had not received any texts all day. I tried to send a few as well and they were unsent. I started uninstalling things I thought may be the problem. Once I uninstalled iRealSMS, my SMS and MMS went back to functioning properly. It is not ready.
I downloaded BiteSMS and it works great. You get a 15 day trial and its still free after that just with ads. I chose iReal over Bite on my 3GS but many of the things I did not like or didn't function as well originally on Bite now work great. If iReal doesn't step up quick with a new version and send me a new license, I am sticking with Bite.