If you’re gonna build a smart grid based on WiMAX, you’d better get partnered with the biggest wireless carrier placing its 4G bets on the open standard. San Francisco-based startup Grid Net did just that on Monday, announcing its WiMAX-enabled products would work on Sprint’s 4G network, which in collaboration with Clearwire is rolling out WiMAX networks across the country. But that rollout has been slow going (I’m still waiting for Sprint 4G in the San Francisco Bay Area), and Sprint and Clearwire have both suggested they might support the rival 4G technology called Long Term Evolution (LTE) being adopted by the other big carriers, including Verizon, AT&T and T-Mobile. All of these telecoms have big, if vague, hopes and dreams for smart grid services — and Grid Net, despite its long-time championing of WiMAX, has also said it will support technologies like LTE. Which begs the question — what other startup partners might the LTE adherents be working with on their smart grid ambitions?