Regular cell phones, like the RAZR and SideKick or something more advanced, like a Palm Treo or Pocket PC?
Most should look fine on the smartphones (Palm, PocketPC etc..). Regular phones, look for low bandwidth since they don't have a lot of memory. Text only or very small graphics.
Blogger will not load up on my LG Rumor (insufficient memory) but it loads up on my PocketPC phone.
WordPress loads up fine w/ my Rumor, but be careful with PHP based applications, some won't work well on some mobile phones.