Those Vodafone-bundles for € 30 (currently only € 20 at some Saturn and MediaMarkt shops) are ZTE K3565-Z, which are a bit more complicated to debrand compared to Huawei modems. There's no real SIM- or netlock on those devices, but the included software won't connect to other networks than Vodafone's, but you can change that by debranding it. Detailed information and instructions are available at
ZTE K3565-Z (Vodafone) - 3G modem wiki
The SIM card in the bundle is not voice-capable.
But the ZTE K3565-Z does only support European 3G bands (900 & 2100 MHz), which makes it useless for American 3G networks (however it still has quadband GSM-support).
You may prefer the "Tchibo Internet Stick", which is a Huawei E160 with support for 3G at 850, 1900 and 2100 MHz, so you could use it e.g. on Rogers and Fido. It currently costs € 30 and is available online and at local Tchibo shops. The Tchibo netlock can easily be removed by entering an unlock code, which you can purchse on eBay.co.uk for ~€ 2 or sometimes even less.
The K3565-Z and the Huawei E160 share the same Qualcomm chipset (MSM6246) limiting their download bandwidth to 3.6 MBit/s and the upload to 384 KBit/s (no support for HSUPA), so they are not the fastet ones.
If you want a faster device with support for American 3G bands, check out the "T-Mobile web'n'walk stick IV", which is a Huawei E176 sold for € 50 (incl. shipping) at German eBay:
T-Mobile web´n walk Stick IV NEU ohne Simlock PORTOFREI bei eBay.de: UMTS-Router (endet 30.12.09 15:31:02 MEZ)
It's unlocked and the T-Mobile dashboard software can easily be removed by running a firmware update, as described at:
debranding Huawei USB modems - 3G modem wiki