I had 4G up until this Monday, September 13, 2010...
I too was loving the 4G speeds I had experienced in Sherman Oaks along Ventura Blvd up until September 13, 2010. The 4G tower is still detected on my Sprint EVO 4G, but not connecting. I called Sprint on Monday to troubleshoot issues with the Mobile HotSpot downgrading from 4G to 3G when the HotSpot was enabled... They seemed to be very suspicious and indicated to me that Sherman Oaks is not really covered and they where puzzled by how I was getting 4G. So, Sprint Support was eager to help on the Mobile HotSpot 4G to 3G downgrade issue and boy they did help... Seems I got kicked of the 4G permanently. After performing a fresh network profile update on my phone, the 4G no longer worked in this area. They had no explanation other saying it is not officially covered in Sherman Oaks...bastards!!! So, I had them remove the Mobile HotSpot feature which saves me $30/month. I use PdaNet from junefabrics.com which allows me to tether without rooting the phone. Had Sprint continued to let me use the 4G network, I would have kindly spent the additional fees for the Mobile HotSpot feature...but they where no longer interested in helping and deferred me to the 4G coverage map... And sure enough, their 4G Map states that it is not covered in Sherman Oaks, CA.
Although I am extremely upset and kept the 4G wireless enabled my phone, I had to turn off the 4G Network notification alert because it was driving me nuts when I am here in Sherman Oaks!!!! It kept reminding me that the tower with full bars is available but I cannot connect. So, for the past week or so I was really enjoying 4G speeds. I almost cancelled my DSL...good thing I removed the the cancellation order for DSL... 3G coverage in Sherman Oaks is really terrible.
Anyhow, I worked in the West Hollywood/Beverly Hills area today and re-united with the 4G network... At least there's hope that 4G will officially be covering the Valley! Thanks Sprint for the tease!!!! You suck!