One of the reasons I didn't buy a Palm Pre today (other than lack of interest) is that I don't want to see a bill from Sprint in my mailbox every month. I already get one from AT&T for my iPhone 3G and frankly, that's more than enough for me.
Even when I'm not using the iPhone as my primary phone, I still make full use of its SIM card and associated voice/data plan. Over the past two years, I've swapped out the SIM and used both the original and second-gen iPhone plans in my HTC Advantage, AT&T Tilt, Sony Ericsson Xperia X1, HTC Shift, USBConnect Mercury 3G modem, and Option GT Max ExpressCard modem. For about eight glorious months during that period, I also had the now-defunct $20 unlimited 3G data service with an AT&T GoPhone. That setup was really perfect for me, especially when traveling, but I've since been making do with a single SIM without much trouble.
Sharing one card with multiple devices is certainly inconvenient, especially since the iPhone SIM isn't accessible without a paperclip, but I don't work away from home enough to justify the cost of a separate data-only plan or some other contract that I can use for tethering or running WMWiFiRouter on. If I traveled more often or had a different job, I probably would've had an unlimited data plan for a USB modem or one of my CradlePoint routers (which don't work with the iPhone SIM) and eventually migrated to a MiFi. But I don't, so the post office delivers just one wireless bill to me each month.
Based on what I've seen in the forum, read on other websites, and learned via email, however, many mobile computing fans, phone geeks, and road warriors receive at least two wireless bills every month. Some people get even more. What about you? Vote in the poll below.
My husband and I will be traveling a little this summer, so I'm currently toying with the idea of picking up a Verizon MiFi and paying for the Mobile Broadband DayPass ($15 for 24 hours) when needed. Even though I'll have to pay full price for the MiFi itself, taking the DayPass route is more cost-effective for my needs.