After playing around with Pownce for a day and a half, invite thanks to Tommy Vallier, I have a few opinions on how it could be improved. I really think they could make this into a Twitter killer if they can make some changes before Twitter improves. I don’t know if Tiwtter is planning upgrades and I do like the simplicity of their service but they need some features that pownce has done well.My first sticking point with Pownce is the lack of mobile access, either via SMS or a mobile app. SMS would be universal and far less support/porting for different phones would be needed. This would hands down kill Twitter for me. I really do beleive that that is where twitter wins. The reply function is a tough one for that but Facebook has got that nailed. If you look at the messages you receive on Facebook each one has a “code” appended to the short code they use. That way when you reply to the message they can identify which message the reply is to. Tiwtter, Pownce and Jaiku coulde implement this and add relpy functionality to SMS fairly easily.They could also use that theroy in their notification emails. Put a code in the subjet line to identify the mesage. One thing I did notice shortly after signing up for the service is by default they send you a ton of emails. If anything happens on your account, friend requets, message posts, etc. they send you an email. This email does not tell you anything other then you have a message. That was frusterating. Tell me the message and let me reply to it. Doing that by emial is one simple way to go mobile for a lot of people as they could use their mobile email address. I do like the control over what they send you via email though. Despite everything being on by default there is a ton of customiziaton in the notifications. Regardless of how they implement mobility this should carry over (eg. I don’t want files or lins sent to my mobile, just messages and events is fine).Their desktop app looks really good. It has a bunch of nice features, like how it goes fuzzy when it can’t connect to the server. I just don’t like having to download and install something (Adobe’s AIR framework) before I can install an application.I think the biggest factor stopping people from moving over is the fact that the people are still on Tiwtter. People will not move on mass away from something that they are comfortable with. This probably isn’t that bad a thing as it will allow them to scale the site instead of the site going down all the time, like Twitter did, because of the load. If people slowly move, for one reason or another, the crowd will follow, as will I. I’m not against this, its called prgress thats how things change. I’m sure I’ll have more opinions over the next while and they will probably improve their service so stay tuned and you might see more!