Everyone has been saying since the beginning that mining is not profitable and you'll never pay for your hardware, but who knows how high the value of Bitcoin will go. If you want to try it out then start by setting up a CPU miner on your computer. Then try GPU mining if you have a decent graphics card. If you're still having fun then invest in a better rig. You might not ever make a profit, but it is an enjoyable hobby at the least.
There are an awful lot of people involved in mining, so I'd venture that some of those people think mining could be profitable. There are a number of BTC mining calculators out there (
http://lmgtfy.com/?q=bitcoin+mining+calculator) that can give you a rough idea of how long it will take to recover your investment in hardware and the electricity you'll use.
The group at Ars Technica ran an experiment using a dedicated miner given to them by Butterfly Labs (one of very few ever seen in the wild). They made about $700 worth of BTC in two weeks. That's some nice money, but realistically very, very few people are going to see those kinds of returns.
That being said, I'm at least putting my $ where my mouth is; I'm waiting for two of the ASIC USB devices to show up. Running 660 megahashes ought to bring me a little coin (pun intended). But I'm not quitting my day job, that's for sure.
