The wireless carriers offer them in one form or another. The most recent news is that ATT is offering their own 3G MicroCell to its mobile customers. I suppose having your own mini tower is a pretty cool thing to have.
But if the wireless providers did their jobs, is there a need for them? Especially in the cities? Luckily for me, I live in an area where most of the networks have pretty good coverage except for Sprint so there isn't a need for something like this in my home or office.
It goes back to coverage and whether you feel the need to pay for a microcell for coverage when you've already paid for it once already. ATT offers their tower for $150 so you can do their job and you still have to use up your minutes for access. And here's the part that gets to me: you have to use your existing Internet connection.
I get the feeling that over time, we'll get used to this sort of treatment. One more thing, ATT is charging extra for this, $20. T-Mobile's @Home service, offers unlimited calling via Wi-Fi, charges only $10 and their equipments cost less than $50.
I'm sure your ISP will love this very much. The funny thing is ATT is advertising better 3G connection. But it appears that while you're connected to it, your iPhone apps like Slingplayer will not work even though you're connected to your own Internet access. So you'd have to switch over to Wi-Fi to get it work.
More rant about this at Gizmodo (great read). They ranted but I'm just pointing out the facts. See, I'm trying to stay positive to neutral about the wireless providers given past negative posts about them. You know, trying to maintain positive outlooks on mobile life.