Finally, some good news in an MVNO market shaken by failures (Ampd Mobile, most recently) and dire analyst predictions. Tween-focused kajeet, launched six months ago on the Sprint Nextel network, announced today that it has secured $36.8 million in Series B venture capital funding.

Draper Fisher Jurvetson Growth Fund (DFJ Growth Fund) led the financing, and existing investors like Bessemer Venture Partners, Fidelity Ventures, Gabriel Venture Partners and InterWest Partners also participated. Randy Glein from DFJ Growth Fund has joined the board of directors at kajeet with the closing of the Series B.

MVNOs have come under fire for a lack of rational business modeling. For its part, kajeet, which has a pay-as-you-go model based on a refillable prepaid wallet of credit, is specifically tailored for kids with specialized ringtones, games, wallpapers and cute little round-headed mascots. The company also offers the kajeet Configurator, which allows users customize the phones while giving parents parental controls. It appeals to parents with its low cost, too: there are no activation fees or contracts, and no flat-rate charges. Voice calls are 10 cents per minute, for instance.

Draper Fisher Jurvetson Growth Fund www.dfjgrowth.com,  www.dfj.com  
kajeet www.kajeet.com