I recently got to play with the Monsoon HAVA Platinum HD, one of three streaming video devices Monsoon is now selling under the Hava name. Like a Slingbox, HAVA sits between your TV and Cable Box/DVR/DVD Player and allows for "placeshifting" of audio-visual content to your PC or smartphone. Monsoon is positioning HAVA as a faster, cheaper, better Slingbox alternative - the Platinum HD version (and the HAVA Wireless HD version) can stream HD content, bring PVR (video recording) capabilities to your PC, and integrate with Microsoft Windows Media Center computers.
The HAVA Mobile Player - currently in Beta - brings a/v content from HAVA to select mobile phones. Currently, around 20 Windows Mobile smartphones can be found on the officially supported list at myhava, though the final entry on the list, "ARM9 based device with 640x480 resolution," suggests wider compatibliity. A post on the user support forums also indicates that a Symbian S60 mobile client is currently in development.
Overall I found HAVA to be a powerful device that's not quite as polished as its Slingbox competitors. While the Platinum HD version trumps Slingbox's HD-compatible "Pro" model in terms of resolution and price, Slingbox is overall a more refined and stable platform. More importantly to you, the reader of a cell phone blog, Slingbox's SlingPlayer Mobile software is currently available in Windows Mobile (Smartphone and PocketPC), Palm OS, and Symbian flavors. Since your smartphone isn't capable of HD resolutions, anyway, Slingbox scores a big one-up on HAVA in the stability and compatibility departments. And they have a Mac client, whereas HAVA is Windows-only for now.
Still, if you're in the market for a Placeshifting device and have a compatible smartphone, HAVA's worth a look. The more expensive Wireless HD model provides the flexibility of integrated 802.11 WiFi so you don't have to run a cable from your A/V setup to your network router, and the HAVA team has been getting great marks for tech support. DIY and hacker types, in particular, will appreciate HAVA's possibilities as a PVR and place-shifting add-on to Windows MCE systems.