Yes it is, because the Acer N35 has, with its USB-Guest port, an USB-Host port, and a RS232 serial port ...
About the USB-Host (which would allow, in theory, to connect to the PDA any USB device), the other day, i read on a spanish forum (--link--), that Acer choosed not to expose this port, because they did not have tested it ennough, and that, then, it might not be 100% functional ...
On the other hand, about the RS232 serial port, it is possible to buy from Acer an adaptator especialy made for the N35 ... or to build it yourself !

Both the USB-Host port and the RS232 port are accessible, like is the USB-Guest port, through the little 26 pins connector.
Given its size, the only mean to access it is to modify one of the two power-supply adaptators ... and, despite the fact that inside pins are also tiny, they are large ennough to permit clean solders (with some calm and with adequat tools indeed !) ...

Once the connector is opened, you'll see, on each face, two rows of pins, of which 2 of them on every sides are welded to black or red wires.
Those wires are those from the power supply who charge the battery of the PDA.

If you opened the adaptator of the synch-cable, you'll find two more wire, one green, one white, which are the USB-Guest wires.

On a russian site (www.pinouts.ru), if found the pinout of this connector. Here is a quick overview :

You just have to solder 8 wires (of different colors if possible, so you can make the difference), and a 9th wire that you will solder on one of the two metal parts.
Once done, if you don't have small insulator tubes, you could try to insert between longs and short rows, a small sheet of paper or carton so they don't make short-circuits which might happen because of the rigidity of your wires ... Oh well, you just have to try to make something clean and safe !

Next, you'll have to make a path so your 9 wires can go out of the connector. On mine, i've just made a little hole into one of the two platic part, and everything went out ... Here, again, you just have to make something clean and safe ...

Then, you can start to solder your wires to a male DB9 or DB25 connector with respect to the conventionnals pinouts ...

Voilà, that's all about the tinkering ...
Now, i'm going to talk about the way this port works with the N35.

If, with a voltmetre, you measure voltages of some outputs pins, you'll probably be suprised (or disappointed) to discover 0V everywhere ... You will, then, tell to yourself that you have miserably failed, that you are too bad to deserve a RS232 port on your N35, that you are damned, haunted, unlucky, idiot, that you should better see a psychologist as soon as possible, or even, and simply, that the author of this article probably made a mistake and that he deserves to go to hell with his RS232 connector plugged deep into his ... Well ... No panic ... 0V everywhere, it's normal !

Yes it is, it's even so normal that if you're finding something else than 0V, then, chances are great that you have miserably failed, etc ... or that the author of this article has made a little mistake into his schematics ...

The RS232 port of the N35 will not be activated without an adequat voltage from the RS232 device. For instance, if you apply 5V on the pin 1 (DCD) of your DB9 connector, the voltage of the pin 4 (DTR) should change from 0V to about +6V or -5V ...
And, if your PDA is off, when the voltage is changing, the PDA should detect it and should switch itself on.

Into the Organisation System, this serial port is "COM1:".

A good mean to test your adaptator could be to connect it to a DCE (a RS232 device), like, for instance, an RTC modem, and to "talk" to it using a terminal emulator (tty) for PocketPC ...

Generaly, RTC modems talk to DTE (terminals) using AT&T commands. For instance, if you tell "AT" to the modem, it should reply "OK".
If you tell him "ATH1D12346674324", it should hook on, and compose "12346674324" ...

You can also try to connect your PDA to the RS232 port of an other computer using a "Null Modem" serial cable, and then try to establish a software connection using on each computer a terminal emulator ...
With null-modem cable, most of the time, only 3 RS232 pins are used (RxD, TxD and GND). On the other hand, with a RTC modem, the 9 RS232 pins are usually used ...