That is true, but it could change. It is very easy to write for webos, since it is based on HTML/CSS/Javascript. So a lot of web developers can get into this.
But HP doesn't seem to be hyping or publicizing this at all. No shout-outs to developers. No "here's our SDK, here are some screencasts and tutorials". They exist, but they aren't being advertised at all. Apple has conferences where they get developers excited about working on apps.
HP's new TouchPad won't have that. It will probably do well, but it won't even touch the success of the iPad. Nobody writes apps for WebOS.