When in doubt of upcoming features, check the text strings.

According to Greek technology site iPhone Hellas, text strings in the most recent beta of Apple's iPhone 2.0 firmware point to new features as well as mention extra steps included to prevent unlocking. The strings mention terms such as "A2DP" and "HeadphoneBT", which could point towards a stereo Bluetooth system as well as a Bluetooth remote control feature.

Other hints within the text strings include an allusion to "RoleGps", which implies GPS navigation as well as an as-yet-unknown reference to printers.

Additional references also mention a new "YouTubePlugIn.webplugin" component for the Safari browser, although current speculation indicates that this software is unlikely to replicate Adobe Flash or provide similar animation plug-ins. Instead, the software is through to provide a dedicated YouTube player to load a given video from a web site. A "Google411" text string may be a reference to Google Maps and suggests that the iPhone may be able to receive either a voice or text directory lookup link for given locations.

Apple may also be taking its first steps to actively counter unlocking attempts. A new, clearly identifiable "BRICKED_AND_SIM_LOCKED_STRING" indicates that the handset may eventually refuse to unlock itself for use with unofficial carriers if it detects that it's been restricted from normal functions, a condition that can occur partway into the unlocking process. While it's unclear that this would avoid hardware hacks or those that can make deeper changes to the firmware, the move suggests Apple has or will have a solution to casual attempts to de-restrict the phone.

The final version of the iPhone 2.0 firmware is due for release in June.

If you've heard anything about this on your end or had a chance to play with the new iPhone 2.0 beta, please let us know over in the comments or forums.